Thanks for the feedback!
You are right! But V2 is already finished, and one of the changes is free repairs after returning. Your mine isn't lost either; when you die, you will get your money back. However, at the moment, you don't really need the mines. Your first buys should be upgrades for oxygen, hull capacity, or flashlight radius.
In V2, the submarine-wall collision is also separated from the sonar collisions, so it's much smoother to drive along the walls (not every single rough pixel will collide with you anymore).
Additionally, the start in V2 is much faster, more comfortable, and more enjoyable.
Feel free to come back after the jam ends and after the update is live to see all the improvements!