Swimming
The ability to swim is a power commonly used in the Rayman series. It is first used in Rayman 2 where Rayman first learns to swim underwater.
In Rayman
Swimming is not one of the powers used by Rayman in the original Rayman game. If he falls into any body of water in the Dream Forest or the Caves of Skops, he will instantly lose a life. It is clear that he hasn't learned the ability to swim yet at this point.
In Rayman 2
In Rayman 2, Rayman is now able to swim underwater, but for only a limited time. He needs air bubbles in order to stay underwater without dying. There are certain bodies of water that Rayman can't go in, if he does, he loses some health.
In Rayman Revolution, it is shown in the Minisaurus Plain that Rayman learns the ability to swim with the assistance of both Murfy and a baby Globox.
In Rayman 3
In Rayman 3, Rayman uses the power to swim mainly in the Land of the Livid Dead. In the fourth phase of the world, it is revealed that he can now swim more freely with his helicopter hair and without needing air bubbles to survive.
In Rayman Origins
In Rayman Origins, the heroes can swim but no longer underwater, until they enter Sea of Serendipity and save the nymph Annetta Fish. She grants them the power to dive in the sea, allowing the team to advance through the world.