Bah, what do you think we are, some nature-loving pansies? BAH I say!
No, cost-conscious pirates!
(It's cheaper to enchant coral with watery stuff.)
Also, I thought about the stronghold, and I have a few options:
1. Giant mass of seaweed. Basically an island made of kelp. Cost: One really powerful druid.
2. Underground base. Tunnels in the rocks below the ocean floor. Cost: Around 30k.
3. A giant submarine. Cost: Probably too much.
4. Anything floating while being supported by ballons, possibly made of whale leather.
1. Uninspiring, and kinda crappy. A barren desert island would be better than a mass of sargasso.
2. How would we get into or out of it? How would our workers get down there?
3. Neat idea, but why make it a giant submarine? Something floating would be a lot cheaper.
4. Meh. Not the worst, not the best.