I just finished giving this a try and I think it has good foundations but could be refined some more. There a bit of information I would have liked be more available while playing the inventory could show the capacity with a number and a cash value of the contents without having to be at the sell shop. I also think the movement speed should be a bit higher, though you would have to rebalance the mining speed and oxygen tank. I think these things could definitely make the game more fun to play in general.
The following are just opinions that may not be faithful to the game vision and I primarily think this because I only got the 1st upgrade in each category.
I think it might be better if mineral density or mineral value were higher. It took me a fairly large amount of time to farm up the cash to get the first upgrades and seeing the 2nd tier be almost 3x as expensive while my cash per dive was not going up at a similar rate had me decide to finish my playthrough early.
The inventory system may be bugged because when the yellow bar for it became completely red I could still pick up more ore.
I don't want this to sound overly negative so I'll say that the sfx were well chosen, though the volume of some and the absence of a block breaking sound is notable.
The full commitment to a consistently scaled aesthetic showed me one way I could improve my own game (the sprite resolution varies wildly).
The art for the shop and seller are charming in their own right, and the character of the shop options text is equally so.
The title screen is pretty and the options menu along with a pause function was a good addition because I didn't add a pause function to my submission at all.
Lastly, I'm very interested in the tools used to create the surface of the water. That is technically incomprehensible to me right now so bravo to that.
Thanks for playing my submission again.
I hope I'll see you in other jams!