Ikoi spa (opens new window) is offering an "enzyme spa", where you are buried in rice bran, sawdust and other organic material. Claims are being made (opens new window) that this can help digestion, circulation and the immune system, but as usual there is no good evidence that it does anything of the sort!

The most plausible benefits probably occur from the mixture fermenting, producing heat. It's pretty unlikely that anything else in the spa is helping your body.