The Season 3 opener: underwater caves off Andros, an island in the Bahamas; how the Georgia Aquarium in Atlanta cares for its four whale sharks.

A shipwreck off Florida where goliath groupers spawn every year; Australia's Great Barrier Reef. Also: how aquatic animals employ color and camouflage to protect themselves, hunt and find mates.

The story of a pilot whale that was found stranded on a Curaçao beach and later adopted by Sea World San Diego. Also: "cleaning stations" that remove parasites and dead skin from ocean denizens, including sharks, sea turtles and eels.

Diving with sea lions off the Galapagos Islands leads Bird to the Mystic Aquarium in Connecticut, where he learns how sea lions are trained. Also: filming humpback whales off Silver Bank, near the Dominican Republic.

A 13-year-old boy learns to dive, then explores the waters of Grand Cayman Island. Also: the dolphin program at the Curaçao Sea Aquarium.

Sea snakes; coral spawning; aquatic creatures that form partnerships in order to survive.

The Muyal-Ha sinkhole in the Yucatan, which is more than 100 feet deep; the biology and diversity of sharks.

An expedition to film the tiny blind cavefish. Also: coral; bottom-dwelling sharks, such as the wobbegong.

The Season 3 finale features the saltfish of the Riviera Maya in Mexico; and the potato cod of Australia, which can grow to several hundred pounds. Also: a virtual dive to the ocean floor from aboard the Starfish Enterprise of Bar Harbor, Maine.