A follow up to my post below.
Here's a Fox News report on the Neptune Underwater Reef.
The "reef" is a man-feature. People's cremated remains are placed into the sculpture/reef and will potentially replenish the reef, nourish the fish, etc.
I can see being interested in this as a final resting place if you were an avid scuba diver or loved the ocean. But I don't buy the whole, "giving back to the earth" angle as a primary motivation, which the CEO pushes.
Heck, if you like the idea, more power to you. Personally, it CREEPS ME OUT!