Semi-submersible may refer to a self-propelled vessel, such as: *

Heavy-lift ship A heavy-lift ship is a vessel designed to move very large loads that cannot be transported by normal ships. They are of two types: *''Semi-submersible'' ships that take on water ballast to allow the load—usually another vessel—to be fl ...

, which partially submerge to allow their cargo (another ship) to float into place for transport *

Narco-submarine A narco-submarine (also called a drug sub or narco-sub) is a type of custom Seakeeping, ocean-going, Marine propulsion, self-propelled, semi-submersible or fully-submersible vessel built by (or for) drug smugglers. Newer semi-submersibles are ...

, some of which remained partially on the surface *

Semi-submarine A semi-submarine (semi-sub) is a surface vessel that is not capable of diving, but has accommodation space below the waterline featuring underwater windows. The watercraft is similar to glass-bottom boats, but with deeper draft. Both types of ...

, which cannot fully submerge *

Semi-submersible naval vessel A low-profile/semi-submersible naval vessel is a hybrid warship, that combines the properties of a surface ship and submarine by using water ballast to partially immerse and minimize its above-waterline profile, thereby improving its stealth charac ...

, which partially submerges to minimize being observed *

Semi-submersible platform A semi-submersible platform is a specialised marine vessel used in offshore roles including as offshore drilling rigs, safety vessels, oil production platforms, and heavy lift cranes. They have good ship stability and seakeeping, better than dr ...

, which is typically transported to a location where it is placed in service * Oil platform, a large structure with facilities for well drilling to explore, extract, store, and process petroleum and natural gas, in deeper water (more than 1,500 metres (4,900 ft)), the semisubmersibles or drillships are maintained at the required drilling location using dynamic positioning.

See also