Typical drilling unit

This is what goes and explores for oil or gas.

Its a typical semi submersible drilling unit. Not the one that I am involved with.
These have pontoons(2) with a typical length of 100/110 meters long and colums (4) on top of which you can see the deck structure and the derrick structure.
Semi submersible is as it says when it is at an operational working depth the unit will have been submerged so that approximately 25 meters of it will be below the water line.
Some are moored with chain and wire and some are Dynamically positioned with rather large thrusters (large rotating propellers).
Types of water depths that are being operated in with some of the modern units can be 10000 to 12000 ft. Quite deep !