I think it is a really neat concept and fills an important role as a means of quickly escaping a bad situation down under, but it can be so awkward to use that it's really not worth the precious space it takes on the hot bar to use. Instead I think with a little tweaking it could become an essential part of the dive kit and not an novelty item that becomes irreverent after building a seaglide or seamoth.
I would find it far more useful if it could be used to quickly descend as well as ascend. I'm picturing a wearable item like a BCD (An inflatable vest used in SCUBA to control buoyancy) that could be activated by a quick double tap of the spacebar or C key (like the minecraft sprint function) or with separate hotkeys. The general idea is that the vest would be weighted, in its default position the bladder would be half filled with air, offsetting the weight of the vest, allowing the diver to maintain position in the water column and swim normally.
Spacebar would fully inflate the vest, consuming a small amount of air and propelling the diver to the surface, pressing the C key once would release a bit of air, returning the diver to a neutral state.
Double tapping the C key would have the opposite effect, expelling air from the bladder causing the diver to descend quickly until the spacebar was pressed. This would re-inflate the vest to its default position, stopping the descent and consuming a small amount of air in the process.
Like the air bladder, whenever air is released the bubble effect would envelope player's field of view. I would hate to lose that cool effect.
I think this would work great with the new paper doll equipment and inventory system being considered for the next game build. Let me know what you think!