AvoINFINAUT

I posted another thread recently trying to get help on how I could efficiently fill in the ocean i had drained in the editor, well i was messing around and somehow using the destroy terrain mode with the biggest brush size in the air bubble under water it somehow created water where the air bubble was, im not sure how to replicate this because it wouldn't work in other places but i thought id just share my findings for others trying to deepen an ocean.

Ive recently tried making a cool cove for my ship to be docked, in the editor. But when I make remove the ocean floor it leaves an air bubble, Ive tried manually terraforming water back into the air bubble but the water always goes above the surface of the original ocean level. If anyone has an idea on how i could do this or a key binding to make the terraforming remain at a certain y level so i can fill in the water without going above the sea level.