Yeah, I know it sounds odd, but I know trees and plants can survive in very extreme conditions. It would have plenty of water and if it wasn't too deep, it could gather sunlight from the surface. Just a random thought.
-
Trees are ill equipped to capture the essential carbon dioxide dissolved in water (as opposed to being present in the air). Moreover, they require evaporation from the leaves to have sap flowing; something that would be impossible to do under water.
-
some plants do they have adapted to those conditions of water but others no it might be to much there is such a thing as to much water