Before I continue, I will say that this was in an old world updated to 44a. However, we (it's a LAN world) had never been anywhere near this area.

The seed for the world is: Heights

Make the world in the first 1.18 snapshot, find yourself in the middle of the ocean, teleport yourself to the nearest jungle biome, and head to the savanna until you reach a large hill. Do /locate for the nearest iceberg. Behold...

You were saying how there wasn't any bedrock in the game. Maybe you could remove icebergs, too? There's a part (I don't have the picture for this) in a mesa biome like this, only the mesa is at least y 150 and it's a straight drop to the ocean.