watery grave
Idiomatic expression for dying at sea and becoming part of the ocean debris. Often used in the phrase 海の藻屑と消える (to perish at sea).
See also: 海の藻屑と消える
He perished at sea.
Many sailors met a watery grave.
Literally 'seaweed scraps of the sea', a fixed idiomatic expression for a death at sea where the body is lost to the ocean.