Transhipment arises when an outport does not have sufficient depth of water or facilities to accommodate deep sea vessels or when the cost of deviating, including extra port charges, makes such a call uneconomical.The outport may then be served by a smaller vessel known as a feeder ship. This plies between the outport, which is then termed a feeder port, and the port served directly by the ocean vessel, known as the transhipment port. This latter type of port is often one which is on a number of trade routes. It specialises in, and has facilities for, cargoes which arrive on one ship and are transferred, or transhipped, into or onto another. It may also have facilities for intermediate storage.