The water boatman is a common water insect with a flat, boat-shaped body and long, oar-like hind legs, which enable it to swim very well. It has a full-grown length of 14 to 16 millimetres. It is greenish white in colour, with yellow to brownish wing cases.
The water boatman can be found throughout Europe and most of Asia in fresh, brackish or salt water.
A highly efficient predator, the water boatman feeds on small aquatic animals, mosquito larvae and young fish. It attaches itself to vegetation at the bottom of the pond or stream and breathes from an envelope of air stored around its body and under its wings.