There’s nothing more embarrassing than dropping a weighted body into a deceptively shallow river. Fishermen don’t have this problem, because they only murder fish, and because depth finders are old hat to them. Still, this wrist-mounted one caught my attention. The Humminbird Smartcast RF30 separates the sensors from the display, letting you attach a sonar transducer to your fishing line and see results right on your wrist display.
