GameDynamo - "Underwater portions of video games generally turn players off. Even in good games, the underwater level is often the weakest part, such as with the Water Temple in The Legend of Zelda: Ocarina of Time, or the deep sea levels in the Super Mario games (complete with all manner of squids, killer fish, and other monsters). This is because gamers and game developers are both land-bound animals, and trying to conceive a fully three-dimensional underwater environment is far outside their everyday comprehension. However, particularly savvy designers have used water to make brilliant and entertaining worlds. Here are ten of the best levels composed mainly of H2O."