Most drones are capable of flying in the air only. The Loon Copter is different. It is a versatile multi-rotor platform that flies in the air, floats on the surface of the water with its sensors below it, and can even perform moves underwater. Since it is buoyant, the Loon Copter does not require any energy to float.
Such a drone could prove useful for underwater search, environmental monitoring projects, and other comparable tasks. More information is available at the link below.