I have a Tesoro Tiger Shark (VLF) and a Whites Duel Field (PI). Both are waterproof. I use them both on the salt beaches in and out of the water. I have been told that the Tiger Shark works better in fresh water than salt, but I really haven't had the opportunity to find deep targets in fresh water so I can't confirm that. The Whites PI air tests on an average size man's gold wedding band at about 13" max. The Tiger Shark about 11" max. However, the PI had to almost touch a thin gold earring to make a sound. The Tiger Shark was sounding off at about 8". You can forget about thin gold chains with the PI unless there is a heavy clasp or a pendant on it. The duel field has an inner loop of about 6" and an outer loop of 11". the inner loop is suppose to see the smaller targets but not quite as deep and the outer loop is suppose to see the larger targets deeper over the whole 11" diameter. I think that part seems to be accurate, but the inner coil does not see the thin, small gold. Supposedly, Whites Duel Fiend PI detector has been programmed to pick up gold better than older models, and have a quicker response time so you do not have to sweep it as slow as older PI models. Can't sweep as fast as a VLF but faster than older PI models. I have found gold with both machines close to a foot deep. I have also found bobby pins and pennies at 18" deep with the PI. I also found a heavy silver bracelet at about 2' deep with the PI. With the PI, I dig 5 pieces of trash for every clad find. Gold is few and far between, but enough to keep me interested. If it ain't there, you're not going to find it with any machine. The PI is more stable in black sand on the beach and no ground balance is necessary whereas the Tiger Shark is manually ground balanced and less stable in black sand. Based on what I have read, I would probably have bought the Minelab Excalibur instead of the Whites PI, if I had it to do over again. The Excalibur goes almost as deep but nulls on iron so you are not digging bobby pins at 18". But then if I was using the Excalibur I would not have dug the $500 dive watch I wear now because it would have nulled on the stainless steel. You give some, you get some. your call. Hope it helps. Ralph