There are people who operate underwater dredges. They have a 5-20 hp engine on them and a hookah rig. They pump up the gravel and pass it over a sluice box where the gold drops out. They use them to tunnel under and then roll big boulders to get whats underneath.
http://www.keeneeng.com/Merchant2/merchant.mvc
I read about a guy that just snorkels and snipes crevices along the bottom, he uses a turkey baster, some screw drivers, chisel and sledge to get down in the cracks and removed the sediment. He pans it later.
I spent some time up in the Sierras and then down in Arizona for the winter. I did it on kind of whim, expecting maybe to find a nugget or two. I did my homework and found what I thought were good places. There's a big problem. All these places were under claim. There are people working these claims, some part time, a few full time. NO ONE wants you on their claim prospecting.
Where are you located, I have books and topos on Wash, Ore, Calif and the Quartzite AZ area.
GPAA has claims and a reasonable fee to use them, there are a few other clubs that do the same. There are some outfits that just don't feel right, that sell memberships. Kind of like time share condos on unpatented land that they only own the mineral rights on.
http://www.goldprospectors.org/
Look around our various forums - everything from New-To-Scuba to Instructors-Only to Dive Medicine.
