[Skarg]

Good question, for other reasons. It always seemed to me that if there really is a lot Mer-stuff going on, it would want a LOT of development beyond what ITL mentions, and depth/pressure issues are just one of many.

I would expect a deep sea gate to the surface wouldn't pass water, but if it did, the GM would need to come up with rulings for what the water does and how quickly the gate breaks down.