Our adventure starts on the Galapagos Islands. This volcanic archipelago is a haven of rare and endangered species. On land you'll find myriad birds, insects, and the islands' famous tortoises. But under the waves, it's a different story. 

Corals have made the rough volcanic rocks their home, as have small fish, which hide in crevices and graze on algae and small invertebrates. Larger fish swim about in shoals, safer here than on the open ocean.

Mammals, such as this playful group of Galapagos Fur Seals, make the most of these warm waters, feasting on the abundant fish and raising their young. Also, apparently, seeing what the local scuba divers are up to.

Lying just off Australia's eastern shores, the Great Barrier Reef is one of the natural wonders of the world. The 'living rocks' of this coral reef support countless sea creatures, including the critically endangered Hawksbill sea turtle.

It's a feeding frenzy for these tuna off Lady Elliot Island, at the southernmost tip of the Great Barrier Reef. The island is young, only a few thousand years old, but it's one of the richest habitats in the sea.

If there's one thing the island is known for, it's the Manta Ray. These flattened sharks seem to fly through the water with ease, gently waving their enormous wings while filtering for plankton with their cavernous mouths.

Brazil might be best known for its rainforests and the mighty Amazon, but its seas are also havens of biodiversity. These dolphins are found in the protected habitat of the Canal de Sela Gineta off the Atol das Rocas.

This Ocean Sunfish off the coast of Bali is one of the heaviest bony fish on the planet. Their huge and unusually shaped bodies may be as large as a car, yet they are gentle giants, filtering plankton and algae as they swim the warm, shallow waters.

The crystal clear waters off the Cook Islands of the South Pacific are home to all sorts of animals, but perhaps none more stunning than the humpback whale. Their size, their song, and their apparent intelligence make them one of the most marvellous creatures in the oceans.