The destroyable rock walls in the caves don't make any sense.
They break the flow of exploration and combat, trap monsters behind the rocks.
Don't seem to add anything from a tactical or gameplay perspective and create this awkward situation where you can see the enemy behind the rock, cannot shoot him and he cannot get to you.
How did the enemy get stuck inside there? How does he eat if it is trapped inside? its illogical.
It makes sense that that is where the sea life breeds, grows larger before venturing out into the larger ocean but how the caves are right now makes that seem wrong from a A life perspective with them trapped behind these walls.
Remove the destructible walls, instead use smaller "choke points" that players have to go thru very tightly swimming on their belly. (this creates great claustrophobia situations and still allows good ambushes) while allowing enemies to transition between parts of the cave system.
Add some destroyable walls/rocks to wrecks and abandoned outposts and beacon stations as this makes sense as some of these would have crashed into the rock and had rubble collapse and build up inside them. make it so you cannot see thru them as that is no longer as needed to "show" that the walls destructible. maybe also improve the texture of these walls as right now they just look like solid masses with little detail.