Dolphin
A Dolphin is a man-made marine structure that stands apart from the main quay or jetty, usually a cluster of piles or a concrete caisson. Mooring dolphins take the mooring lines of a ship, while berthing dolphins are fitted with fenders and take the berthing impact.
Dolphins are widely used at tanker and gas jetties, where a ship is held between a central loading platform and a spread of berthing and mooring dolphins connected by catwalks. They allow a long ship to be moored safely without a continuous quay wall along its whole length.
Dolphins let a terminal moor a very long ship — a large tanker or gas carrier — against just a few isolated structures instead of a full-length quay, cutting the cost of the berth while spreading the mooring and berthing loads exactly where they are needed.
What is the difference between a mooring dolphin and a berthing dolphin?
A berthing dolphin is fitted with fenders and absorbs the impact of the ship coming alongside; a mooring dolphin holds the ship in position by taking its mooring lines. A jetty typically has both.