The supporting columns may be moved up and down by a hydraulic or electrical system. The whole rig can also be jacked up when the supporting legs touch the seafloor. During transit, the platform floats on its hull and is typically towed to a new location by offshore tugs. Jackup rigs provide platforms that are more stable than semisubmersible platforms but can only be placed in relatively shallow waters, generally less than of water.
The rig acts as a kind of platform. This type of rig is almost always used in connection with oil and/or natural gas drilling. There are more jackup rigs in the worldwide offshore rig fleet than any other type of mobile offshore drilling rig. Other prominent types of offshore rigs include semisubmersibles (which float on pontoon-like structures) and drillships, which are ship-shape vessels with rigs mounted in the centers. These rigs drill through holes in the drillship hulls, known as moonpools.