Minecraft wiki entry for Ocean_Ruins, associated text: Parts of a larger ruin peek out of the seabed.
Underwater ruined Village.
Chest found inside a larger building with multiple rooms.
Ruins generated beside a Badlands.
Small ocean ruins generated in Lukewarm Ocean.
A chest located in an ocean ruins building, that is hidden by a block, viewed in Spectator mode.
Another screenshot of an ocean ruins structure.
Underwater ruins generated within a coral reef.
A ruined village inhabited by drowned.
The drowned can sometimes spawn in positions that they can't get out of.
A large underwater ruin structure.