The Neptune Memorial Reef is an underwater columbarium in what was conceived by the creator as the world's largest man-made reef at a depth of 40 feet (12 m) ). It was originally conceived by Gary Levine and designed by artist Kim Brandell and known as the Atlantis Reef Project or the Atlantis Reef As of 2012, the Reef occupies a one-half-acre (0.20 ha) space, but a planned expansion 16 acres (6.5 ha) is underway. The city design involves underwater roads leading to a central feature with benches and statuary.

Burial at sea is the disposal of human remains in the ocean, normally from a ship, boat or aircraft. It is regularly performed by navies, and is done by private citizens in many countries.