Aqua Drones are Space Pirate Sentry Drones modified for underwater use. They are similar to their Sentry Drone 'cousins' in terms of A.I., but lack the arm-mounted turrets present in the other model - perhaps these were incompatible with water. As such, the Aqua Drone maintains the compact patrolling form of the Sentry Drone even when an enemy is detected. Their only attack is a red beam cannon, which is fired from a turret beneath the optical device. The Drones are only seen to extend their arms when they have been destroyed.
The Space Pirates were unable to develop shielding from electrical attacks, making them vulnerable to Samus' Wave Beam. They only can be found in the wrecked Space Pirate Frigate, Biohazard Containment. Once she leaves the room, Samus will never encounter them again.
Mechanoid: Aqua Drone
Security mecha adapted for use in underwater areas.
The Space Pirates have adapted a number of Sentry Drones for use in liquid environments. These Aqua Drones utilize an arsenal and artificial intelligence suit similar to their cousins. The Pirates have been unable to properly shield these drones from electrical attack, making them vulnerable to the Wave Beam.