I tried an "Authentic Japanese Ganbanyoku rock-bathing yoga experience" at Iyashi spa in Toronto. It was amazing. Bed-rock yoga is similar to hot yoga, in that you are in a hot room, but opposite to hot yoga the room itself is not heated, but rather the floor (or specifically 'bed' made of bedrock) is heated.

The yoga class is 1.5 hrs in total, and begins with a half hr of rock bathing. which is basically lying on the bedrock floor (on a personal space about the size of a yoga mat) and letting the heat penetrate your body. After half hr there is a break and then the yoga begins. The yoga is called yin yoga, and involves only seated and lying down positions in order to have the most contact with the bedrock at all times.

I found this class to be more of a stretching class then specifically yoga. It was more about letting the heat massage your muscles into increased flexibility than specific poses.

In short it was great. I loved the experience and the heat was not over powering nor did it make me feel faint. I really enjoyed the class and the instructor.

The only negative is the price. It was $50 for the 1.5hr class. They do offer deals for a package of classes but they are still quite pricey. I do recommend trying it though cause if you can afford it, it is a great way to relax, stretch and come out feeling rejuvenated.