We had a nice one for using under water when we were scuba diving, but we sold it some years ago. Argh, I can't even remember the brand!
Frankly, we gave up metal detecting because of all the laws and rules. Depending on the State or Federal laws, you can't hunt on other people's land without permission. Anything you find belongs to the landowner, unless you write a contract prior to treasure hunting detailing who owns any finds. Anything found in the waters around here (especially in Florida, where you might want to go diving for Spanish gold and silver) belongs to the State. Anything Native American must be repatriated to the relevant tribe -- and if the tribe can't be identified, it belongs to the State. No hunting on Federally owned lands. No hunting on State owned lands. No hunting on known historical sites without express written permission (like, say, a known Civil War battlefield that may not be a State or Federal park, but is known to have been a battlefield). Any finds of any potential historical or anthropological nature (and since the USA has very little history, that pretty much means everything) belongs to the State, no matter where it is found (even on your own land!).
That left us with treasure hunting on our family lands, or being sneaky thieves and liars and working other people's lands. We just didn't have any joy in it anymore. We're too "goody two-shoes", I guess! Every find made us cringe with worry about whether we were breaking a law, stealing a cultural artifact, or desecrating a Native American burial site. Pop-tops were the only thing you could find and be sure you weren't breaking a law! -- unless you put it back, and then you're littering.