Ok so this week my venue is running a tournament where ALL LEVELS OF TERRAIN ARE UNDERWATER. Now, my question is what powers can allow unhindered movement through this scenario. I assume swim, phasing/teleport, and leap/climb (even though it doesn't make sense) can, but what about flight. The rulebook says that flight ignores hindering terrain, but in a map like this where no flier could fly above the water, what happens?
Please explain your answers.
(p.s. I know that there are multiple threads covering the topic of water terrain but I felt that none of them applied to my specific scenario so I created a new one)

Rule-wise: anything that ignores water terrain or hindering terrain for movement would let you get around it. This would include Phasing/Teleport, Leap/Climb, Flying, and Swim.

Note that with a special scenario it would be better to ask your judge. He may just consider all squares to be water terrain in addition to other terrain types, or he may have special rules in regards to things like flight.

Agreed. By the way, if this is a Golden Age game "Frog Legs" can be fun.

Its silver age and i believe feats are allowed. What does frog legs do?

Lets you use the Swim ability.

http://www.hcrealms.com/units/wsF001.jpg