In this episode of Tech Diving On Air, host Tamara sits down with Gaëlle Giesen, a Swiss physicist, engineer, and deep-diving explorer whose work bridges the gap between science and extreme underwater environments.

Together, they dive into the rigorous preparation and mindset required to execute world-record-setting cave dives. Gaëlle shares her unique perspective on the intersection of physics and diving, explaining how her scientific background informs her approach to risk management and problem-solving at depths exceeding 200 meters. From the emotional toll of writing "goodbye" letters before a major dive to the controversial topic of establishing rules and regulations within the deep-diving community, Gaëlle offers a candid and thought-provoking look at the realities of pushing human limits underwater.

In this episode, we discuss:

- Deep Diving: How a background in astrophysics translates to the practical engineering and problem-solving needed for extreme exploration.

- The Record Breaker: Gaëlle’s experience setting the women's world record for open water rebreather diving (222m) and her subsequent 230m cave dive.

- Calculated Risk: The mental preparation required for extreme depth, including the difficult process of writing "testaments" and accepting the inherent dangers.

- The Ethics of Exploration: A candid discussion on the lack of official governing bodies for deep diving records, the potential need for standardized rules, and the balance between personal freedom and safety.

- Finding Your Team: Why the success of a deep dive relies entirely on the trust and capability of the support team, and how to build a crew you can rely on.

- What's Next: A glimpse into Gaëlle's upcoming projects and new exploration goals.

About the Guest: Gaëlle is a French deep diver, skydiving champion and scientist who was Tamara’s student in Mexico when she learned Sidemount. Gäelle works for CNES, the space agency in France, and has been mentored by a community of deep divers who she has learned and trained with to achieve what no other woman had done before.

Connect with Gaëlle:

Facebook: https://www.facebook.com/profile.php?id=100095601341531

Instagram: https://www.instagram.com/gaelle.giesen/

LinkedIn: https://www.linkedin.com/in/ga%C3%ABlle-giesen-ph-d-a19b456a/

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In this episode of Tech Diving On Air, host Tamara sits down with Vickie Siegel, a marine technology entrepreneur, cave diver, and co-founder of Sunfish—a company developing highly advanced autonomous underwater vehicles (AUVs).

Together, they explore the fascinating intersection of cutting-edge robotics and technical diving. Vickie shares the incredible story of how the Sunfish robot was born from a desire to map unexplored underwater caves and has since evolved into a tool capable of navigating some of the planet's most extreme environments—from the depths of Wakulla Springs to the icy waters of Antarctica, and perhaps one day, the oceans of Jupiter's moon, Europa. They discuss the unique challenges of building a robot that can think for itself in a cave, the differences between ROVs and AUVs, and how these machines are not replacing divers, but working alongside them to push the boundaries of exploration.

In this episode, we discuss:

- The Birth of Sunfish: How a casual conversation about mapping caves led to the creation of an autonomous, hovering underwater robot.

- ROVs vs. AUVs: Understanding the difference between a tethered remote-controlled vehicle and a robot that can think and navigate independently.

- Cave Diving Robots: Why navigating a cave is one of the hardest challenges for an AUV, and how Sunfish uses sonar and spatial AI to find its way.

- From Florida to Space: The journey from testing in Wakulla Springs to being tasked by NASA to develop technology for exploring extraterrestrial oceans.

- Robots and Divers as Teammates: How technology like Sunfish can assist human divers in data collection, infrastructure inspection, and reaching depths beyond human limits.

- The Future of Underwater Exploration: What's next for the Sunfish team, including the development of new "Nova fish" and the ongoing quest for full autonomy.

You can learn more about Vickie Siegel and her team's work by searching for Sunfish AUV online, or by following their ongoing projects as they continue to explore the underwater world.

About the Guest: Vickie Siegel is the co-founder of Sunfish. She’s also a badass cave explorer, expedition leader with experience in running complex logistics in extreme environments.

Connect with Sunfish and Vickie Siegel:

🗣️JOB OPENING AT SUNFISH CLICK HERE 🙌

• ​Website: https://sunfishinc.com/
• ​LinkedIn: https://www.linkedin.com/company/sunfishinc/posts
• ​Facebook: https://www.facebook.com/sunfishinc
• ​Instagram: https://www.instagram.com/sunfish_auv/
• ​Email: [email protected]
• ​Alaska project summary click here!

If you enjoyed this episode, please follow the show and share it with your dive buddy.

Changing the culture starts with a conversation.

Contact me: [email protected]

Don’t forget to subscribe! One click helps our team continue growing the project and reaching more divers! Thank you 💙

In this episode of Tech Diving On Air, host Tamara sits down with Jerónimo Avilés, a Mexican speleologist, paleontologist, and the Director of Instituto de la Prehistoria de América AC.

Together, they take a journey back in time, exploring the Ice Age megafauna that once roamed the Yucatan Peninsula and now rests deep within its flooded caves. Jerónimo shares his extensive knowledge and passion for these submerged time capsules and the remains of the ice age megafauna. From the giant ground sloth (Xibalbaonyx oviceps) to the elephant-like gomphotheres, they discuss the incredible biodiversity that existed here over 10,000 years ago and the meticulous work required to study and preserve these fragile remains. Jerónimo also explains the crucial difference between a mammoth, a mastodon, a gomohoterium and a gomphothere—much of it is in the teeth!

In this episode, we discuss:

• ​Time Travel Underwater: Understanding the Pleistocene epoch and how rising sea levels preserved a treasure trove of fossils in the cenotes.
• ​Meet the Giants: A detailed look at the unique species found in the Yucatan Peninsula, including the giant sloth, gomphotheres, and even prehistoric bears and llamas.
• ​Teeth Tell the Tale: How paleontologists use dental morphology to distinguish between species and understand their diets and environments.
• ​The Importance of Context: Why moving a bone, even slightly, can destroy valuable scientific data and the story it tells about the past.
• ​Ear Bones & Evolution: Jerónimo's fascination with auditory ossicles and what these tiny bones reveal about an animal's life and evolution.
• ​Citizen Science: How divers can contribute to paleontological research by documenting their findings responsibly and reporting them to experts.

About the Guest: Jerónimo is a researcher, photographer, cave diver and paleontologist whose work has derived in dozens of scientific and outreach papers. He has spent almost 30 years diving, documenting and studying the caves, archaeology and paleontology of Quintana Roo.

Connect with Jerónimo Avilés:

• ​LinkedIn: https://www.linkedin.com/in/jer%C3%B3nimo-avil%C3%A9s-olgu%C3%ADn-segovia-b3bb604b/
• ​Facebook: https://www.facebook.com/jeronimo.olguinsegovia
• ​Instagram: https://www.instagram.com/jeronimoavilesolguin/
• ​Email: [email protected]

If you enjoyed this episode, please follow the show and share it with your dive buddy.

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In this solo episode of Tech Diving On Air, host Tamara takes the mic to share a candid and insightful look at the nuances of being a model in underwater photography. Drawing from six years of experience working with various photographers in challenging environments like caves, Tamara discusses her personal "pet peeves"—the things she wishes photographers wouldn't ask her to do.

Far from being just a list of complaints, this episode offers valuable advice for photographers on how to work more effectively and respectfully with their models when trying to portrait realistic cave diving practices.

Tamara explains the safety concerns, practical limitations, prioritizing conservation and aesthetic preferences behind her dislikes, from being asked to look away from the guideline to dealing with uncomfortable posing requests like holding a static scooter. She also touches on the importance of authentic representation, explaining why she avoids wearing makeup for shoots and prefers capturing genuine moments of exploration over staged scenes. Whether you're an aspiring underwater photographer or a diver interested in modeling, this episode provides a unique perspective from the other side of the lens.

In this episode, I discuss:

• ​Safety First: Why asking a cave diver to turn their back to the line or swim away from it into decorated areas is a major "don't."
• ​Authenticity vs. Staging: The preference for capturing real action and movement over static, posed shots that can look awkward or fake.
• ​Lighting Logic: Why pointing lights in unnatural directions can ruin a shot and feel wrong for an experienced diver.
• ​The "Look" of Tech Diving: A discussion on makeup in technical diving photography and why a natural look is often more practical and compatible with the gear.
• ​Equipment Etiquette: The importance of giving models time to clean up their gear and align their trim before snapping the photo.
• ​Communication is Key: How discussing shots beforehand and respecting a model's comfort zone leads to better photos and a safer dive.

If you enjoyed this episode, please subscribe to the show, leave a review and share it with your dive buddy. Changing the culture starts with a conversation.

Do you know a great speaker that should be on this show? Let me know!

In this episode of Tech Diving On Air, host Tamara sits down with Dr. Jason Gulley, a hydrogeologist, researcher, and award-winning photographer whose work has taken him from the depths of glacial caves to the hidden world of the Florida's springs.

Together, they explore Jason's remarkable journey from a scientific career focused on glacier caves and aquifers to becoming a visual storyteller for National Geographic. Jason shares the pivotal moment a chance encounter with a manatee changed his perspective on photography and conservation, leading him to document not just the animals, but the complex environmental challenges they face. From the technical challenges of photographing in pitch-black caves to the patience required to capture intimate moments with wildlife, Jason reveals the dedication behind the images that inspire us to care about our planet.

In this episode, we discuss:

• ​From Science to Storytelling: How Jason transitioned from academic research to using photography as a tool for conservation and communication.
• ​Manatee Magic: The unexpected encounter that sparked a passion for documenting manatees and the different personalities within a herd.
• ​The Florida Springs Crisis: Understanding the environmental threats facing manatees, including pollution and habitat loss, and the importance of looking at the bigger picture.
• ​Technical Challenges: The realities of underwater photography, from dealing with buoyancy in rebreathers to using specialized optics to overcome low visibility.
• ​The Art of Patience: Why the best wildlife photos often come from spending hours simply observing and waiting for the right moment, rather than chasing the shot.
• ​Global Manatee Perspectives: A look at the different manatee species around the world, from the Amazon to West Africa, and the unique challenges they each face.
• ​Advanced camera equipment, housings, lenses, optics and brand recommendations.

About the Guest: Dr. Jason Gulley is a hydrogeologist who specializes in water, glaciers and climate change research.

He is also a science and expedition photographer with experience in several continents, some of his remarkable work has been conducted in Alaska, Greenland, Nepal and Africa.

He is a cave and CCR diver.

Connect with Dr. Jason Gulley:

• ​Website: https://jasongulley.smugmug.com/
• ​Instagram: https://www.instagram.com/jason_gulley_science?igsh=b292M2FlMmxtZ3h0
• ​LinkedIn: https://www.linkedin.com/in/jason-gulley-aa507b214?utm_source=share&utm_campaign=share_via&utm_content=profile&utm_medium=ios_app
• ​Latest work: https://www.nationalgeographic.com/environment/article/florida-rodman-reservoir-ocklawaha-river-springs?loggedin=true&rnd=1768324477494&fbclid=IwdGRleAPvhtxleHRuA2FlbQIxMQBzcnRjBmFwcF9pZAo2NjI4NTY4Mzc5AAEeF5pc5sG1ykqiQh2E8JHjRLwht9915LYmhXUKDp6ExA2A-rlAiKWK6V2CvWs_aem_r2CdJtyDsr4qMJDNffMQpA

If you enjoyed this episode, please follow the show and share it with your dive buddy.

Changing the culture starts with a conversation.

Contact me: ⁠⁠⁠[email protected]⁠⁠

In this episode of Tech Diving On Air, host Tamara sits down with Dr. Dario Gomez, the hyperbaric and diving physician in charge of the Costamed hyperbaric chamber system and the DAN (Divers Alert Network) Liaison for Mexico.

Together, they tackle one of the most critical yet often misunderstood risks in diving: Oxygen Toxicity or commonly known as "Toxing out". Sparked by their initial meeting during Tamara’s own treatment for Decompression Sickness, this conversation covers the practical knowledge between medical theory and diver safety. Dr. Gomez breaks down the physiology and what happens when our body's protective systems go into place when oxygen partial pressure increases, he explains the delicate balance between oxygen as a life-saving treatment and a potential harmful element. From the terrifying reality of underwater seizures to the controlled environment of a hyperbaric chamber, they demystify the limits that keep divers safe.

In this episode, we discuss:

• ​Defining Toxicity: The difference between Pulmonary and Central Nervous System (CNS) oxygen toxicity and why divers need to worry about both of them.
• ​The Numbers Game: Why recreational diving limits are set at 1.4 PO2, technical diving at 1.6, and how hyperbaric chambers safely treat patients at 2.8 atmospheres.
• ​Anatomy of a Seizure: Understanding the role of free radicals and oxidative stress in causing a "jump start" of the brain, and what a seizure actually looks like.
• ​Warning Signs: How to recognize the symptoms before a convulsion occurs, including muscle twitching, tunnel vision, nausea, and confusion.
• ​Susceptibility Factors: Why physiology varies from person to person and how CO2 retention, or heavy exertion can lower your tolerance to oxygen.
• ​Emergency Response: The immediate first aid steps for DCS and toxicity symptoms, and why administering 100% oxygen on the surface is still the gold standard.

About the Guest: Dr. Dario Gomez is a specialist in hyperbaric medicine and the Medical Director for the Costamed Hyperbaric Clinic in Cozumel. As the DAN Liaison for Mexico, he is at the forefront of treating diving injuries and educating the community on dive safety. He is also an avid diver who understands the practical challenges of staying fit while diving frequently.

Connect with Dr. Dario Gomez:

• ​Website: ⁠⁠https://world.dan.org/⁠, ⁠https://www.costamed.com.mx/servicios/camara-hiperbarica⁠
• ​Facebook: ⁠https://www.facebook.com/DiversAlertNetwork⁠
• ​Instagram: ⁠https://www.instagram.com/diversalertnetwork/⁠
• ​LinkedIn: ⁠https://www.linkedin.com/company/divers-alert-network/⁠
• ​YouTube: ⁠https://www.youtube.com/@DiversAlertNetworkTV⁠

If you enjoyed this episode, please follow the show and share it with your dive buddy.

Changing the culture starts with a conversation.

Contact me: ⁠⁠[email protected]⁠

In this episode of Tech Diving On Air, host Tamara sits down with Dr. Efraín Chávez, a Postdoc, researcher at UMDI Sisal, part of UNAM (National Autonomous University of Mexico), and cave diver who specializes in the ecology of groundwater fauna in the Yucatan Peninsula.

Together, they dive deep into the super interesting but overlooked world of the fauna in the cenotes, challenging the common misconception that caves are lifeless voids. Efraín bridges the gap between rigorous scientific research and technical exploration, revealing the fascinating evolutionary adaptations of "stygobitic" creatures—animals that have evolved to thrive in total darkness. From the evolutionary process and the energy-economic process of losing one's eyes to the critical health state of the aquifer, they discuss why these tiny, blind creatures are the canaries in the coal mine for the region's water quality.

In this episode, we discuss:

• ​Life in the dark: Dispelling the myth that caves are boring or dead, and understanding the complex ecosystems thriving beneath our feet.
• ​Evolutionary biology: How and why species like the blind fish (Typhlias pearsei) and blind shrimp lose their sight and pigment over generations.
• ​The cast of characters: A closer look at the unique inhabitants of the Yucatan cenotes, including the rare blind eel, isopods, and the ancient, centipede-like Remipedes.
• ​Conservation and threats: The impact of pollution, over-extraction, and climate change on the fragile groundwater systems and the 67 documented species within them.
• ​Citizen Science: How divers can contribute to research through photography, utilizing tools like iNaturalist and supporting the Cenoteando initiative.
• ​Practical identification: What to do when you spot a "cave critter" and how to distinguish between different species during a dive.

About the guest: Efrain lives and works in Merida Yucatán and has developed a thriving technical diving career and professional diving path as a GUE diver among others. He’s passionate about the environment, research and the hands on experience of making science in places most scientists will never reach.

Connect with Efrain Chavez: 

• ​Website: https://cenoteando.mx/
• ​Facebook: https://www.facebook.com/cenoteando.org
• ​Instagram: https://www.instagram.com/el_efracs/
• ​LinkedIn: https://www.linkedin.com/in/efrainchavez/?originalSubdomain=mx
• ​E-mail: [email protected]

If you enjoyed this episode, please subscribe to the show, leave a review and share it with your dive buddy. Changing the culture starts with a conversation.

Do you know a great speaker that should be on this show? Let me know!

In this episode of Tech Diving On Air, host Tamara sits down with Bernardo Rotzinger, the operational heart of Cuzel and the man ChatGPT has officially dubbed "The Valve Wizard."

Together, they explore Bernardo's journey from fixing compressors as a teenager in his family's business to becoming a leading expert on high-pressure systems in the Mexican cave diving capital. They dive deep into the mechanics that keep divers alive, discussing the crucial engineering differences between valve types and the terrifying consequences of equipment negligence. Bernardo bridges the gap between industrial engineering and diving, explaining why knowing what happens inside your tank valve is just as critical as checking your gas.

In this episode, we discuss:

• ​The Valve Wizard's Origin: Growing up in a dive shop, taking over the family business at 18, and blending hands-on mechanics with self-taught engineering.
• ​DIN vs. Yoke: A technical breakdown of why the industry is (and should be) shifting to DIN, including the safety limits of the clamp system versus the captured O-ring design.
• ​The Explosion: A harrowing first-hand account of a filling station accident caused by mismatched threads, highlighting a deadly risk often invisible to the average diver.
• ​Nautec Valves: Why these German valves are considered the gold standard—from lead-free brass alloys to the "non-memory" properties of the internal seats.
• ​The trends that CCR diving is bringing to Mexico and how the businesses adapt to supply it.
• ​The Safety Gap: The lack of formal certification for filling station operators and why "I've always done it this way" is a dangerous mindset in technical diving.
• ​Maintenance: Why your valves need service just as much as your regulators.

About the guest:

Bernardo Rotzinger is a 33 years old Mexican engineer, cave diver and filling station manager who grew up at the Cuzel filling station. His father, the founder of Cuzel, started the business to fulfill a higher standard when back in the 80s it was difficult to find good quality air for divers.

Today, he is one of the most knowledgeable technicians in compressor, filling, tank and valve maintenance in Mexico.

Connect with Bernardo Rotzinger: 

• ​Website: https://dive-nautec.com/
• ​Facebook:  https://www.facebook.com/profile.php?id=100054533705791
• ​Instagram: https://www.instagram.com/nautec_mexico/
• ​E-mail: [email protected]

If you enjoyed this episode, please subscribe to the show, leave a review and share it with your dive buddy. Changing the culture starts with a conversation.

In this New Year’s episode of Tech Diving On Air, host Tamara shares three practical tips to help you achieve your goals — from using visualization to make them real and attainable, to understanding the resources your dreams require, and intentionally making time to pursue them.

Tamara also looks back on the biggest highlights of 2025: launching this very podcast (800 listens, 160 subscribers, 6 episodes!), traveling to Diving Talks Portugal to connect with explorers and creators, committing to a meaningful fitness journey, continuing the Vanilla Farm exploration project with Jack Cleary into its second year, growing a small cave-diving business with the support of students and friends, and completing GUE Fundamentals with Ivo from Third Dimension — a challenging, eye-opening class that helped debunk myths about GUE culture, highlighted flexibility in training, and deepened her understanding of procedures shaped by GUE methodology.

She also reflects on the year’s biggest challenges — adapting long-built muscle memory, managing mental and physical fatigue after months of teaching, and being pushed (in a good way!) by GUE’s outstanding and detailed e-learning platform.

Just when she thought the year was over… a brand-new, last-minute project appeared — and she’s hopping on a plane to join it. Which leads to a bonus fourth tip: recognize opportunity, grab it when it arrives, and do what it takes to learn from it.

Happy New Year — and see you in 2026! Thanks for listening.

In this episode of Tech Diving On Air, host Tamara sits down with Dan Sun, entrepreneur, founder, and driving force behind Dan Sun Titanium—a Hong Kong–based company dedicated to creating titanium tools for divers.

Together, they explore how Dan has quietly redefined what high-performance titanium dive tools can be, and the challenges of entering manufacturing without a formal engineering background. Obsessed with precision, Dan operates at the rare intersection of innovative tool manufacturing, rigorous problem-solving, and deep respect for the people who rely on this equipment—divers and explorers who simply don’t have time for failure. While creativity opens the door, functionality always remains the top priority.

In this episode, we discuss:

• How Dan Sun Titanium was born, including the story behind the “perfect” titanium wrench
• Why titanium is the perfect material and her love/hate relationship with titanium
• The realities of manufacturing in the scuba industry: supply chains, production processes, and specialization
• The design rabbit hole—how to evaluate good ideas, understand why some fail, and turn the right ones into reality
• The less glamorous side of entrepreneurship, including the less fun but essential work that leads to excellent customer service
• The production of non-titanium products and the release of a Cenote Girl imited edition item made with Dan Sun especially for exploration. Check it out here!!!

About the guest:
Based in Hong Kong, Dan Sun runs her company while spending much of her time traveling and diving. With a background in corporate HR, she made a complete career pivot after investing in her first production run of 30 titanium spanners—and then taking on the challenge of selling them herself.

A self-taught engineer and entrepreneur, a woman in scuba diving manufacturing, a boat captain, and a rebreather diver, Dan brings a perspective that is both inspiring and refreshingly grounded. Her stories and insights make this episode well worth listening to.

Connect with Dan Sun: 

• Website: https://www.dansuntitanium.com/
• Special https://www.dansuntitanium.com/product-page/ocean-tactical-series-explorer-pouch
• Facebook: https://www.facebook.com/dansuntitanium
• LinkedIn: https://www.linkedin.com/company/dan-sun-titanium
• E-mail: [email protected]
  

Sponsor: This episode is brought to you by Seaya Underwater Lighting Systems.

With lights on, we explore more.

https://seaya.com/en/

https://www.facebook.com/seaya.dive.lights

https://www.instagram.com/seaya.dive.lights/

If you enjoyed this episode, please subscribe to the show, leave a review and share it with your dive buddy. Changing the culture starts with a conversation.