https://www.youtube.com/watch?v=R1Bve8YcEhI
Semi-submersible rigs make stable platforms for drilling for offshore oil and gas. They can be towed into position by a tugboat and anchored, or moved by and kept in position by their own azimuth thrusters with dynamic positioning.
A semi-submersible (semisubmerged ship) is a specialized marine vessel used in a number of specific offshore roles such as offshore drilling rigs, safety vessels, oil production platforms, and heavy lift cranes. They are designed with good stability and sea keeping characteristics. Other terms include semisubmersible, semi-sub, or simply semi.
Credits: badfishcastle
