Personally, I'd like to skip the "cremated" part. It uses a lot of energy, and folks who live nearby have "issues" with the facility!
Thank you for writing. Great idea being part of a reef for the sea creatures to use. Thank you for calling my attention to the ‘problems’ with the cremation process. I can remember smelling the ‘smoke’ from the bio incinerator at the local hospital when I lived in Anniston, AL. IIRC, someone told me the chimney was not tall enough ... I have no idea on that one.