Semi-submersible ships are the only vessels in the world which provide the capability to load, transport and offload extremely heavy cargo, such as oil drilling rigs, gas refineries or even warships. The giant ships literally sink until their decks are below water, the yachts in transit are sailed on, and the ships lift with the boats on board. At the other end of the trip, the ship lowers, and the boats are sailed off, ready to go. It's something like a car ferry, but for yachts. Their large, free and open deck makes them the largest heavy transports in the world. They are capable of loading lifts from approximately 50 to as much as 45,000 tons. Many of the larger ships of this class are owned by the company Dockwise, including the Mighty Servant 1, the Blue Marlin, and the Black Marlin. In 2004, Dockwise increased the deck width of Blue Marlin, to make it the largest heavy transport carrier in the world.

Sea giants