Food for thought ACE, for a deep water detector. Ask yourself this question: Are you diving in fresh water or salt, or both? In my opinion the Sand Shark is a great machine as junk lord stated, I own one. I have owned the Garrett Sea Hunter Mk II and it too is a great machine and is waterproof to 200 feet. I like the fact that the Sea Hunter has interchangeable coils, just be very careful with the tiny prongs in the connector. The P8X to me is more geared toward commercial diving and treasure hunting, the price reflects this. These are all Pulse Induction units which shine in saltwater environments, but have no discrimination. I do believe that once you are used to using a PI unit you can determine some targets by the way they sound, but this is not always the case. PI typically are not great in freshwater because of the lack of disc. and the fact that iron will not rust away quickly in freshwater and tends to litter the bottom of lakes and rivers, can be very frustrating. I have been in more than one diving situation where I had to find items for people, all I had was a PI unit, I was unable to find the items because of surrounding iron in the search area. If you want tone ID, discrimination in salt or fresh then I believe in the Fisher CZ-21, also little things steer me to the CZ. Things like volume control on the face with deep target boost, headphones that are comfortable and stay in place over my neoprene hood and have equalization ports with tethered plugs (this feature is really nice), and the unit is built like a tank. It all boils down to what your budget is and what environment you are diving in. I didn't mention the Minelab Excalibur but it would be another choice, I don't care for the null over iron but that is a personal thing and not a fault of the machine necessarily. PI units are typically always deeper seeking than VLF units, and that is another thing that you have to decide, are you willing to dig very deep holes for a fishing hook or a bobby pin? Having said that, if you want to find small gold chains, the PI units may give you a better chance. The Tesoro Tiger Shark will find chains and is an excellent VLF machine but is a single tone machine, but has a great discriminator. I personally choose the CZ because for me it is a perfect balance between ease of use, tone ID in salt, and reliability, and the fact that you can use it for land hunting (hip mounted preferably) although not as sensitive to small items as a dedicated land machine because of the circuitry used.
