My gym's recovery fitness options include a sauna, a cold plunge and a hot tub. The sauna easily gets the most play. Sometimes there are so many people in there that hopefuls are forced to wait outside, shivering in their swimwear. The cold plunge is also really popular, but on a rotational basis. People tend to pop in for two minutes or so, often monitoring their process via a clock on the wall, as if performing a plank, then swap out.