Thank you for your find!


I had not come across that thread when I created this one.
It seems they never got past the depth thing

They are surely more ways how to  utilize potential gain but unfortunately there is no gain. Was doing a bit of calculations.
This idea is based on assumption that we can retrieve all energy that we spent on compression. Yes, we can retrieve all energy during decompression when the diver is at the top but thats not possible when he is at the bottom. 


Problem is with air bubble in the diver. Suppose that diver is at the top and we compress its air bubble so its volume got one liter smaller spending energy E. With diver at the top the same amount of E is needed to regain that one liter of volume. But when diver is at the bottom with higher water pressure using only E will not regain one liter of volume, it will be less. To get it inflated to original volume extra work is needed and this work is exactly (in ideal system with no losses) what could be possibly gained from diving motion to bottom.