To attend your first Cirque du Soleil show on the Las Vegas Strip is to come to the realization that the only limit to one’s imagination is a closed mind. Never is this more evident than in “O," the groundbreaking production that’s been taking the “Wow!” factor to new heights (and depths) since the equally groundbreaking Bellagio opened its doors in October 1998. What sets “O” apart from other Cirque productions (or, really, any show anywhere) is how water plays such a vital role in the story—what other theater production’s centerpiece is a 1.5 million-gallon pool that doubles as a stage?

Performing above, in and under that “stage” is a cast of 77 acrobats, characters, synchronized swimmers and divers (including eight former Olympians) from 22 countries. That cast, as well as the eight musicians and one vocalist who perform live at each show, are supported by more than 120 stage technicians (including 14 underwater) who pull all the innovative strings behind the scenes. Together, the cast, crew and one-of-a-kind elements have made “O” not just an award-winning show but a true Las Vegas institution that’s entertained more than 16 million people. And to think: It all started with a little imagination.

Bellagio, 7 & 9:30 p.m. Wed.-Sun., $98.50-$155 plus tax and fee. 702.693.8866