A method of recovering a deposit from the sea bed using a surface vessel (20) untethered from the sea bed and first and second suction vehicles (27; 30) which traverse the sea bed to suck up the deposit and are each connected to the surface vessel by a respective flexible riser (26; 29) along which a slurry of the deposit is transferred from the suction vehicles to the surface vessel. The method comprises moving the first and second suction vehicles to and fro across the sea bed in a plurality of lanes such that they travel substantially further than the surface vessel, turning or reversing each vehicle at the end of each lane in a manner such that the lanes are adjacent to one another to mine the deposit substantially without gaps between adjacent lanes. Only the suction vessels rest on the sea bed.