Unlike airborne, here aren't many creatures that could be considered aquatic. The only ones I can think of are Water creatures, Horned Frog and nymphs. Right now, applying certain effects to Water creatures is more practical than applying them to aquatic creatures.
We have to differentiate 2 types of species:
-What can live underwater.
-What can take advantages in the water.
1st category apply to water creatures and acquatic plants, and we can think to a
defensive ability like the "cloack when underwater".
2st category apply to horned frog and to a lot of animals still not used: Crocodiles, reptiles (Jesus Christ Lizard too), turtles, several snakes, worms,duckes and some kind of insects too. These are creatures which may not be included in
cards, like the other airborne non
creatures.
Generally they hunt or feed, so they increase their
attack or speed or allow to
reproduce it in a HUGE number.
So we can differentiate these in 2 natural abilities:
Acquatic.
Amphibian (
http://en.wikipedia.org/wiki/Amphibian (
http://en.wikipedia.org/wiki/Amphibian)). To this we can build a skill like the airborne theme.
I'm interested in particular in speed theme or moviment theme, which is a mechanic not so used in the game except for adrenaline.