An aquascooter apparatus including a controller for preventing problems associated with water leakage into the aquascooter. The aquascooter has a battery, a driving motor and a clutch in a housing, and the controller includes a water leak detecting sensor that detects a leakage of water into the housing. A motor control is responsive to the signal from the water leak detecting sensor, and prevents the battery from supplying electric power to the driving motor responsive to this signal. This prevents electrical energy from being used if a water leak is detected, and therefore prevents any possibility of a dangerous situation of a spark in contact with hydrogen gas.