Search Systems is based in the United Kingdom, so the Mariner's predilection for damp climates and marshy area is a natural fit. Unlike the U.S. Navy's in-development duck-like drone, the Mariner is not a swimmer, but a floater--moving about on the water's surface while its camera looks underneath. To help it in that task, it has special lights to pierce the depths of the lake or stream below, illuminating the algae-covered riverbed. In appearance, the Mariner looks like a tiny submarine with a mechanical spider squashed on top. Six rotors give it lift, and a waterproof body with flotation devices and a bubble canopy give the appearance of a highly sophisticated pool toy.