This idea was originally suggested by Flipside: http://undertowgames.com/?p=240#comment-140

After thinking for a while, I came up with an idea for implementing multiple submarines into the game that can interact with each other without breaking the physics simulation.

The ships that move around in the world can be large, single objects, and the inside of the ships can be static objects hidden in usually inaccessible parts of the map.
When the moving objects in the world bump into something, forces to the objects inside the ship can be applied accordingly. Rotating the moving objects in the world can modify the gravity inside of the ships.
Leaving a ship will teleport the player into the world, entering a ship will teleport the player to the hidden inside of the ship.
The inside of the ships can be rendered seamlessly on the position of the moving objects, so players wouldn't notice that entering the ship is actually teleporting them to another part of the map.

If the idea doesn't seem to make sense I'll try drawing something that explains it better.

Thanks for the idea, that sounds like a much better way to handle the submarines! The current system is kind of a hack and this would be a much more elegant solution. Now the ship can't even rotate, not to mention having multiple subs in the same map.

Well, It doesn't have that much bugs anyways, and doesn't need to be updated all the way to v1.1 like SCP: Containment Breach! xD

Airplane611 wrote: It doesn't have that much bugs anyways,

That's.. Hrm.. Very debatable.