The invention relates to a transfer plant, especially for loading and unloading ISO containers from container ships at seaports, comprising a vertical support which is propped up on the land side and on which a horizontal extension arm is braced. Said horizontal extension arm, along which a horizontal conveying device can be displaced, protrudes across the ship that is to be unloaded on the sea side. The horizontal conveying device cooperates with hoisting and lowering devices which pick up and put down the containers. The aim of the invention is to create a redesigned transfer plant and a method for loading and unloading containers, preferably ISO containers, from container ships in seaports, which allow the transfer rate to be significantly increased and consequently the lay times of the container ships at the pier to be substantially reduced. Said aim is achieved by disposing at least two horizontal conveying devices (9, 10) on the horizontal extension arm (1.4, 1.5, 1.6), which can be displaced independently of each other along said horizontal extension arm (1.4, 1.5, 1.6) between the hoisting and lowering devices (11, 13) that are located on the land side and the sea side. In addition, intermediate storage devices (12, 14), into which the containers can be placed and from which said containers can be picked up by the hoisting and lowering devices (11, 13) that are located on the land side and the sea side and the horizontal conveying devices (9, 10), are disposed on the horizontal extension arm in the area of the hoisting and lowering devices (11, 13) that are located on the land side and the sea side.