The bottomless pit
A multi-billionaire has decided to build a dungeon for real as a commercial venture. This is not your reasonably-convincing or VR version. It is a full-blown, full-sized dungeon based on a typical RPG.
The instigator, whose name is Donald Munchausen (or DM for short), wants to make things as true to fantasy as possible but he lives in the real world so he cannot use magic. However he can use pretty much any current technology.
His aim is to provide as real and thrilling an experience as possible without actually seriously injuring his customers.
How, using only modern technology and no magic, can he simulate a bottomless pit?
The requirements are that a participant who falls into it will feel as though they are falling forever. They will experience the terror and loneliness but, when the game ends, they can safely and quickly be recovered from the "pit" in good physical (if not mental) condition. They should be able to "fall" continuously for at least a day, although that would be rare as these pits usually occur near the final stages of the adventure.
Before entering the dungeon, participants have psychological tests and are warned that the experience may be terrifying in the extreme but that they will ultimately be safe. They have to sign a waiver absolving the company from all responsibility - including accidental death or injury - and of course post-traumatic stress disorder.
Please ask for any necessary clarifications before answering.