In this Minecraft Seed featuring a land-based ocean ruin you spawn on a small island inhabited by turtles. Just offshoe you’ll find two more underwater ruins. All have chests.
In this Minecraft Ocean Ruin seed for Java Edition there’s more than just an ocean ruin. There’s an ocean ruin within a fishing village… and there’s icebergs…
In this Update Aquatic (or higher) seed for Minecraft (Java Edition) 1.13 or higher you’ll find a surface ocean ruin at the spawn point leading to an underground ravine.
This Minecraft 1.13 seed provides quick access to a few Update Aquatic features. Spawn on an island near an ocean ruin (and monument).1.13+ Java Edition.