You are making very limited progress toward the cliff... the spire you dropped off of is still closer.
It is impossible to see what is biting at you in the inky waves until they surface in their frenzy- little piranha-esque fish, except they are covered in spines as well as possessing hundreds of black teeth.
It is a Strength roll to swim back to the spire, made Easy because you are going with the current. It presses you up against the spire when you roll a 4, and the carnivorous fish leave you alone when Vash fires a few shots into the water. He is trying to hit you but misses; the spire shields you.
You are still in the water and will have to scale your way up if you try to climb.
Rianna will take advantage of the fact that at the moment the spire is keeping Vash from actually hitting her and climb out of the water back onto the spire.
She's also at this point afraid and angry enough at this situation that she's probably not able to fully keep control of her emotions anymore...