When a ship sinks in a shallow, high-traffic area, it must be removed. But once it is filled with water it is too heavy to lift so it must be cut into smaller pieces. Fortunately the weight of the ship underwater can be useful when cutting from bottom to top with a cutting wire.
A cutting wire for ship salvaging is a big thick cable with some segments of abrasive materials – ceramic and some synthetic diamond. Cutting wire is passed under the shipwreck after all its fuel is removed. Preparations take some time, because condition of the ship has to be taken into account. This cable is then stretched between two platforms that can be floating or fixed to the seabed. Then it is moved back and forth with a huge amount of pulling force. It easily slices through the ship from the bottom to the top, leaving a relatively clean cut.
After the ship is cut into pieces separate parts have to be raised to the top, which is also quite difficult. They are heavy and lose a lot of structural integrity. These pieces go straight to a company that deals with scrap metal. Then the seabed has to be cleared from the remaining debris.