The "O" Theatre is built around a 1.5-million gallon pool that drops 17 feet below the rest of the stage. The theatre and the massive water tank were custom-built for Cirque during the construction of the Bellagio, before the casino's opening in 1998.
During parts of the show, performers need to stay under water for as long as 90 seconds at a time. Regulators allow swimmers to breathe underwater during the performance, and 24 underwater speakers allow the SCUBA-certified performers to hear music and cues.
The 53 by 90 foot stage is segmented into four parts, controlled by sophisticated hydraulic lifts. The seven lifts can raise the stage from the floor of the pool, 17 feet below, to 18 inches above water level.
Stage level is just the beginning of the "O" performance. The show takes place from the depths of the 17-foot pool to 60 feet above the stage -- a team of four high-divers leaps from that height in every show.