These are the sites where targets at depth are reachable with the right coil

Waterproof to 20 meters

and most general detecting

the X-TERRA PRO separates a dime from adjacent iron at a few inches

IP68 to 5 m (16 ft)

Teknetics Eurotek Pro Metal Detector w/ 11" DD Double-D Coil, Coil Cover, and Tek-Point Pinpointer metal-detectors These are the sites whereTeknetics Eurotek Pro Metal Detector with 11 DD Waterproof Search Coil, Coil Cover, Tek Point Pinpointer, and a Five Year Warranty. The Eurotek Pro features Adjustable Iron Audio, Variable Breakpoint, Variable Iron Discrimination, Superior Iron Separation, Fast Recovery Speed, Iron Identifier LED, 5 Segment Depth Indicator, 3 Tone Audio ID, Ferrous & Non Ferrous ID, Depth Indicator, Motion Discrimination Mode, Discrimination Adjustment, Adjustable