At NASA’s Neutral Buoyancy Lab in Houston, astronauts train for space walking underwater, in a giant pool about half the size of a football field. Jonathan gets a rare and fascinating look into this high-tech diving as he ventures underwater with astronauts.

In a remote part of Andros Island in the Bahamas, a deep crack in the ground leads into a beautiful and stunning underwater cave system. Jonathan joins a veteran cave explorer to plumb the crystal clear water in the depths of Stargate Blue Hole.

Jonathan travels to the island of Bonaire to take a course in freediving from Karol Meyer, a world-champion freediver. Soon he learns how to hold his breath and dive—with no scuba tank!

Jonathan travels to upstate New York to learn how biologists are working to save the sturgeon in the St. Lawrence river. During a dive he films an amazing spectacle that has never been recorded before!

Jonathan travels to Mexico for an up close encounter with Bull sharks, infamous for the fact that they are known to be the most dangerous species of shark to humans.

Jonathan travels to Bonaire to meet an exceptional group of injured military veterans who are learning to scuba dive as a form of physical therapy.

Jonathan joins a group of volunteer divers as part of an international event called the Great Annual Fish Count to take a census of marine life across the globe.

Jonathan investigates the world's fastest fish!

Jonathan travels from Australia to Indonesia looking at interesting bottom-dwelling sharks that don’t look like sharks!

Jonathan searches for an elusive blind cavefish in a cave in Mexico!