Complex sentence: Radiance of the Seas is the first cruise ship to feature pool tables, which are stabilized by a computer-controlled gyroscope, that adjust with the motion of the ship to keep the table-top level with the horizon.
Split into simpler sentences: Radiance of the Seas is the first cruise ship to feature pool tables that are stabilized by a computer-controlled gyroscope. They adjust with the motion of the ship to keep the table-top level with the horizon.