What is life like on a deep sea oil rig?

It is different. A offshore rig worker works on a rotational schedule. Generally, work is a straight 14 day hitch. In many foreign countries, a common hitch is 28 days. This would be called a 28/28, as you get 28 days of work and 28 days off work. The company pays for your transportation from your home base to the rig site.

There are no holidays. Hours are long. Accomodations are cramped.

For every job on a rig, there has to be two people, typically a day shift person and a night shift person. Bringing alcohol aboard a rig is prohibited. There may be special smoking rooms. All rigs have workout rooms.

Life means missing special occasions with friends and family. The internet and the many forms of communication helps greatly in this manner.

Work hours may exceed 12 hours, but you don't have to worry about meals, laundry or a commuting to work, so it doesn't seem that hard.

I've included a link on offshore life.