The engines I designed are able to work underwater as MHD Drives. However, there have been disagreements on the speeds and use on the discord. My application on the Plumeria refit (link is wip, will change on approval) has the ship being able to submerge and go 300 kph with shields down and 800 kph with shields up (since these shields can change their geometry and be used to supercavitate). The Plumeria has submerged in RP, specifically the Eucharis. Some people dislike the idea of spaceships submerging in general, citing Professor Farnsworth from Futurama saying that they're only built to handle atmospheric pressures between 0 and 1. I think some planets have thicker atmospheres, and don't necessarily subscribe to this thinking, but I am wondering how how much depth is possible. (I think that water pressure increases by one atmosphere every 10 meters/33 feet, though 'atmosphere' could mean the water pressure at sea level? That's unclear). I am also not married to these Plumeria speeds, but I feel like standards should be defined. The Plumeria is, at least, an aerodynamic/hydrodynamic shape. Perhaps some standards can be established here? Please provide input. I am open to changing the Plumeria 2E's listed speeds. They're just based on Discord recommendations.