Thanks for the feedback!
These controls are actually version 2.0 of my original idea. Because the character is swimming, I felt there should be some momentum mechanics to keep things challenging. Originally, I had the player tap the key for every stroke they did in the water. Now, it just applies some directional velocity.
I'm glad you liked the clutch-refill (good name for it) mechanic! I wasn't sure anyone would notice, but I wanted those moments to cause a little panic in the player :)