I did a bunch of underwater detecting in Korea and might I suggest you get an actual waterproof detector or scuba detector (handheld). That Garrett Pinpointer Pro has such as small detection area/radius that its impractical for using it other than its intended purpose. You will want something with depth, which the pinpointer does not have. I will root for Garret allllll day, but on the handheld scuba detector game they are lacking. Bang for your buck, I recommend you get a Quest Scuba Tector or the one from Nokta. These are hand held, but actually have decent depth and coverage. On the other hand if money isn't a problem, Garrett has waterproof machines that will give you crazy depth and coverage; like the AT Max for example. The Minelab Excalibur is also a diving favorite.