hey cold get a boat with side scan sonar at that depth and a target that large find a fisherman with a hummingbird 1187 it has gps go out ping it mark it plan it dive it put a jersy up line till you are 10 feet below surface put a cheap bouy on it ( 5 gal plastic jug) then you can dive it at will and be safe about it a sweep search in low viz is neither safe or sound judgement. always in for a good hunt be safe.
