I did spend a lot more time underwater learning the combat there. It's actually really challenging since your aggro bubble is 3 dimensional.
This is somewhere in the Kessex Peak region. Yes, that is a shipwreck.
Apparently turrets are disabled underwater (which is good, they don't exactly float). I couldn't use any good healing skills. Party battles are hard to coordinate here but, the good news is that you just need to surface to regen health and rally - far easier than on land. One thing that GW2 did very well is to make underwater battle not just a rehash of land battles. It really is a different experience although within the same rules.
This is what you surfacing to breathe and regen looks like. The monsters will try to dunk you back under though. That's always fun.