How pressure differentials could enhance gameplay and engineering in water.

Part 1 - Ship design considerations:

Fortunately we already know that water pressure exists and that water can be separated from an air volume by blocks. What we don't know is whether this can impact your engineering decisions outside of flood prevention so here is how water and air pressure differentials could impact those decisions. First it creates risks, now a player has to stop and think about how they are going to explore the oceans rather than simply crashing their ship into the water and strapping an underwater thruster to it because their ship could crush if they dont do things right. If they don't intend to go very deep this might be alright as long as they design a ballast tank, a device that uses pressure differentials to control buoyancy. It sounds complicated but all the player has to do is find a way to use pressure to suck water into the tank when they want to descend and push it out when they want to ascend. Maybe a piston just pushes the water out and pulls it back in again.

If the player does want to go deep though they would have to consider hull design maybe it needs to be very thick to withstand the pressure difference or they use air pressure to create a hyperbaric sub to save on weight but that comes with its own risk and benefits highlighted in part 2.

Part 2 - The impact on the player character and NPCs:

By introducing air pressure, risks are created directly for player characters and NPCs that can impact how a player approaches an underwater challenge. Normally games kind of hand wave this challenge away by killing the player if they go too deep thus creating the need for a submarine. However, given this is an engineering sandbox game it would be better for pressure to determine how the play approaches a challenge rather than applying a hard limit. Therefore, I propose that player characters should become saturated with gas as they go deeper so when they come up, if they dont do it right, they get the bends and maybe even die. Adding this part of real world underwater diving allows for a more interesting gameplay risk than simple death and the doors for more submarine designs are opened. On one hand you might want a combat sub so you keep the interior at sea level pressure so you can quickly surface and escape in a pinch but on the other hand you might create a hyperbaric sub so that you can explore on foot but you risk not being able to get away from danger if you haven't decompressed yet. The primary benefit of this is that the player is simultaneously pushed by gameplay to build a submarine while still having the option of walking on the seabed. This is because without pressure risk they could jetpack to the bottom and wont need a sub, but an instant death depth would eliminate sea floor exploration.

Conclusion:

By emphasising the role of pressure differentials in the final game players can be presented with a lot more interesting challenges resulting in more varied and less 'meta' designs where form clearly follows from function. Implementation doesn't necessarily require any complex systems to have the desired effect on gameplay. Both water and air pressure already exist in the game hence why water shoots out quicker when you open a damn at a lower point and why you can pressurise a ship. So comparing those with a blocks durability shouldn't be too difficult, at least not compared to the rest of the game. For character saturation a saturation value could tick up and down as you ascend and descend and the bad effects kick in when the value is judged to be going down too quickly.

Thank you to anyone who read I hope you give a thumbs up and tell me what you would like to see out of water.