Ibusuki Sunamushi Onsen Saraku (Sand Bath)

Saraku is a sand bathhouse on the shore at Ibusuki, run by the Ibusuki Onsen Machizukuri Kosha, a foundation.

Hot spring water rises through the beach and heats the sand above it. Bathers change into a yukata, walk down to the shore and lie in a shallow trench, and an attendant covers them to the neck with sand. The weight and the heat bring on sweating within about ten minutes. Afterwards bathers rinse off and use the indoor baths and the sauna.

The spring water comes to the surface on the shore at around 80 degrees, and steam can be seen rising from the beach. The sand is black and coarse, thrown up by the volcanoes that made this coast. Because the grains are large, air passes between them while a bather is covered.

The water is a sodium chloride spring, which is to say a salt spring, and is not simply heated seawater. It holds about a third of the chloride of seawater and is thought to be ancient seawater trapped deep underground.

In July 1985 a team from the medical school of Kagoshima University measured the bath's effects on the body, among them a rise in cardiac output and in core temperature.