Gliders are buoyancy-driven mobile assets. They change their buoyancy by drawing in water through their nose, making their front end heavy and causing them to sink through the water. To float back up to the surface, a motor pushes the water out. Their wings provide lift allowing the gliders to move forward as they change depth. Due to their efficient design, with no need for propellers or an engine, gliders can be deployed for several months at a time.