I kind of see it- but it's tough to know exactly where.
When it mentions the spring vents and "bouying" the guests- it reminds me of a local spring/swimming hole we have here in the Austin area of Texas called Jacobs well. It's an underground/underwater cavern/cave system that feeds a river here. But what's cool is you can jump from a rock into the opening (15' diameter or so) and you never have to swim- because the spring is constantly pushing upwards, its makes you simply bob there above the surface. It's a unique feeling as it is pushing you upwards as opposed to most currents, like lazy rivers or ocean currents that push you laterally.