Fisher 1280X

The 1280X Aquanaut is a fully submersible detector built for the surf and for wading, and it has been doing that job largely unchanged for decades because the design works. It is a straightforward machine with a threshold and a discrimination control rather than a screen full of numbers, which is exactly what you want when you are working waist-deep in moving water. Very stable in salt, very hard to break, and still the sensible choice for a first proper water detector.