This was some of the most physically challenging freediving I have ever done. Going deep (as far as I've gone) was much easier.
For the second dive I decided to use my Starfins Hyperfin. A great idea, with caveats. I was able to hold station against the current by staying in 'ground effect' - the boundary layer along the bottom. But then there was the problem of aiming the camera. One hydrodynamic slip up and I was 100 yards downstream in shallow water; bouncing off boulders and trying not to have my camera smashed, or my suit shredded on the sharp rocks, while being unable to stand due to the mono (made my way to the bank and grabbed roots with one hand to get back upstream...). Best not to slip up.
Bringing the camera up for a shot - or raising my head against the current, was like inflating a drag chute. Actually putting together a composition against all those forces (not to mention being perpetually out of breath from exertion) was an interesting challenge.
Over deeper water I could effectively sprint upstream, but it was exhausting. Then there was the matter of finding something to hold onto on the bottom - and working the available angles.
The Sturgeon are great, docile, beautiful beings. Getting close was no problem - getting a decent picture? A whole 'nuther.
When I did manage to get down into the bottom boundary layer and upstream of the fish - the Sturgeon would form up in my lee. I did a couple of dives without the camera and it was pretty awesome to have a pod of those huge creatures just inches away.