The piston corer recovers the stratigraphically longest sediment sections (up to 30 m). A 1.5 tonne head weight is mounted on top of a number of 5 m long steel barrels that are filled with plastic tubes attached to the barrels by a core catcher. A trigger arm is attached to the head weight, connected by a wire to a small 1 m-long trigger core extending to just beyond the end of the core barrel. When the trigger core penetrates the sea floor, the head weight is released and the piston corer freefall into the sediments. An internal piston produces a weak vacuum in the tube which causes the sediment being cored to enter and move up the tube without disturbing the sediment layers. When the corer returns on deck the plastic tubes are extruded and cut into 1 m-long sections.