Scanning parks and beaches with one of these can be a unique and fascinating hobby.

We independently review everything we recommend. When you buy through our links, we may earn a commission. Learn more› By Tim Heffernan Tim Heffernan is a writer who covers air and water quality and ...

"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." Whether stashed by Captain Kidd or as a plot point in The Goonies, buried treasure has a certain allure ...