Coral Reef?

I remember the coral reefs of total annihilation water maps.
Any chance of them making a return?

I don't see why not, you just have to be carful with the water level.

I'm guessing if they were implemented, they would would act like mountains on planets, and craters on moons.

Personally I'd like them to be passable by small boats but block large ships, subs and torpedoes.

Coral should be passable by subs, you'd just have to surface. I'd think torpedos would be ok too, those typically don't travel too deep, do they?