At Cocos island, there are many whale sharks that roam around the water, gulping down krill and plankton. They swim out in open water, not too far from the surface, where krill is very popular.

Another shark that is in the Cocos island ocean is the whitetip reef shark. 

These sharks travel in large groups, hunting for prey. They are even active at night, always chasing fish around the coral reef.

There are also a number of bottlenose dolphins at Cocos. They like to go out in the open as well, jumping out of the water to eat fish after they push them up to the surface.

Another popular species at Cocos island is the manta rays.

They swim in deeper water, and usually travel alone, although they sometimes can be found in small groups.

Orcas are another type of animal that like to swim at Cocos Island, but are extremely rare, and are known to actually kill sharks, even though everyone thinks that sharks are the biggest predators in the sea. But the truth is, orcas are not dangerous to humans because an orca has never killed a human, in the wild. But some have killed human staff members at amusement parks and stuff because of their brutal treatment. 

Whales also roam the waters of Cocos and it is them that eat many of the plankton, but whale sharks also have a part in that. 

There are sea lions, sea turtles, and over 250 species of fish to see diving. If you stay for long enough, 250 different species of fish should keep you busy for quite a long while.