semisubmersible

noun

1. A specialised marine vessel with good stability and seakeeping characteristics, often used in offshore roles such as oil drilling.
2. A tourist vessel that rides low in the water, with the majority of the vehicle submerged, with underwater windows.
3. A low-freeboard vessel, capable of being incidentally submerged, with the majority of the hull located underwater.

adj

1. (alt-of, alternative, not-comparable)Alternative form of semi-submersible.