If underwater objects like vaults and t3 structures cant be purged, perhaps they should decay much quicker. We have a gigantic base on #1974 opposite Buccaneers Bay which has at least 100 vaults underwater, all connected by t3 foundations/walls. It’s probably responsible for a good portion of the servers poor performance and would take a ridiculous amount of resources to remove - the base itself for much of its existence owned by inactive players who periodically log in to reset the timer and keep it present. This kind of base should NOT be safe from Purges - or anything else underwater.
Either that or add an underwater purge variant.