It is legal to be buried at sea in the USA. You basically wrap the body in a sheet with some weights, at least 3 miles from shore and throw it off the boat. The Navy even has a program to assist veterans of the armed services.
According to one researcher, ancients such as Alexander the Great were sometimes buried in honey. After about a hundred years, candied corpses were supposedly dug up and eaten as medicine.
A company in Georgia, USA will mix your ashes following your cremation with cement and drop it to the bottom of the ocean to form an artificial reef.
The guy who discovered Pluto is on his way there as you read this.