Carlsbad Cavern is a labyrinthine, underground wonderland full of massive cave chambers, otherworldly rock formations and hordes of bats. Rachel and Matt take you on a tour of New Mexico's subterranean Cool Stuff in this episode.

Located in Provence, France, this river canyon is the second-largest gorge in the world. With numerous trails and routes, the gorge offers an unparalleled experience for everyone from professional climbers to weekend enthusiasts. Tune in and learn more.

The Tour de France is a grueling bicycle race that lasts for three weeks and winds its way through some of France's most formidable terrain. Who thought up this crazy race? Who participates in it? Learn more about the Tour de France in this episode.

Siena is a beautiful city in Tuscany famous for its Gothic architecture, medieval character and a centuries-old horserace called Il Palio. Find out what the Palio's all about -- and why winning it is a huge deal -- in this episode.

Japan is famous for its winter wildlife, especially of the feathered variety. Meet the strikingly colored red-crowned crane -- and watch its unique courtship dance -- in this episode.

In this episode, Rachel and Matt take you on a tour of Guatemala's beautiful Lake Atitlan, courtesy of the guys from the "Stuff You Should Know" podcast and an organization called Cooperative for Education.

On the beaches of Costa Rica, Olive Ridley sea turtles perform mysterious, synchronized reproductive rites called "arribadas." Learn more about this mass nesting behavior -- and where in Costa Rica you can watch it unfold-- in this episode.

Mexico's Sea of Cortez is a strange juxtaposition of desert and sea. Meet some the sea's most playful marine inhabitants -- and discover firsthand why it's called "the World's Aquarium" -- in this episode.

Traditionally known as Chinese New Year, China's Spring Festival is a time of feasting, fireworks and good fortune. Join Rachel and Matt as they discuss Chinese New Year traditions, from red envelopes to housecleaning, in this episode.

The Indian state of Rajasthan is a land of desert sands, sturdy fortresses and colorful cities. Explore the impossibly blue-hued city of Jodhpur -- and meet some of its unruly denizens -- in this episode.