The waterproof pulse induction field is very limited at this time. It divides into two classes. Pulse induction metal detectors that ground balance, and those that do not. A pulse induction (PI) detector by its nature tends to ignore mineralization, so much so that in milder conditions a PI works fine without a ground balance circuit. As I noted above however a PI is not immune to mineralization. A non-ground balancing PI detector will sound off when raised and lowered over true black sands