Abstract: Sea-based transportation and load handling system, comprising a ship of the catamaran type, having two hulls being arranged at a distance from each other and a deck (4) connecting the upper portions of the hulls, where the hull sides of the hulls are facing each other and being adapted for moving a load unit (2) in between the hulls, the load unit (2) substantially occupying the space between the hulls, and couplings (5) being arranged in the sides of the load unit (2) and in the hull sides to ensure interconnection of a load unit (2) with the two hulls of the catamaran.