To quote from the FAQ on their website,
"An Eternal Reefs Memorial Reef is a designed reef of cast concrete that can include the cremated remains of a loved one. These Memorial Reefs create new marine habitats for fish and other forms of sea life."
The most wonderful thing from my point of view is that you are able to participate in this. On the show, I saw a widow and her young son remembering their husband/father.
This service is available for pets, also. Or, you can be "cast" with the remains of your pet(s). Or other human loved ones (deceased, of course).
You can even pre-plan. (important note, I have no personal knowledge of this company, or this service, and can not endorse. I am just passing this along as something of interest.)
We don't like to think of death, but as we grow older....well, those thoughts come more and more.