Asilomar is a state-run recreational facility on the California coast, where for many years (from the 1960s through the 1990s) there was an annual Mensa event which was the forerunner of Regional Gatherings, though there is some terminology dispute over whether Asilomar itself should be considered an RG. Unlike normal RGs, Asilomar was not affiliated with any specific local group. The Asilomar gatherings were very popular, and always sold out their limited attendance slots (the registration fee included on-site accommodations, so the number was limited by the number of rooms in the facility).
Mensa Asilomar had a reputation for hedonistic activity, and was strictly limited to attendees over 18 years old. Favorite features of Asilomar included speakers, beach olympics, a world-class treasure hunt, the casino with somtimes risque costumes, and a Sunday-morning auction featuring MensaBucks. Many of these have been copied by other Gatherings, but never duplicated. In later years, as attendees became older, most of the vaunted hedonism faded. But there are still stories about notable incidents, such as the satyr chasing the virgins through the casino, or Nicki and the phone booth. You'll have to ask someone who knows.
The last Mensa Asilomar gathering was held in 2000. Management had changed a couple years earlier and they increasingly wanted to focus on high-profit corporate groups rather than low-profit private groups like Mensa. They became progressively more restrictive, forcing Mensa to move the hospitality suite off-grounds, requiring Mensa to purchase all supplies through the management company, and even attempting to prohibit parties in guest rooms. Eventually, the management company decided to not renew contracts with Mensa or any other private group. There is a story that untoward behavior by Mensans contributed to this decision, but as noted above, by 2000 Mensa Asilomar had become rather tame.
There have been abortive attempts to start similar gatherings elsewhere, under titles such as "Son of Asilomar", but they have not been successful.