the airtight aspect would be the same for space and underwater, but had a nice little debate about pressure. Space is a void, so the structure would be geared toward holding the ship together from flying apart outward. Under the ocean, the pressure would be the opposite, pressing IN on the ship. But we agreed that it would work for both purposes because the void of space is much greater than the ocean, so the ship would be sturdy enough to hold together in both. Scotty did complain about what the salt water would do to his ship, though.