Isobe Spa was used long ago by travelers coming and going on the Nakasendo route, and just before the town of Karuizawa was opened up as a cottage area in the Meiji Era, the spa was a very lively spot. It is also the birthplace of the internationally recognized icon for an onsen（♨）which was first displayed to represent Isobe Spa on an illustrated map in 1661 accompanying the judgement providing ownership rights to the land for the spa.
The current Isobe Spa includes 8 hot-spring hotels quietly standing in a row with the local fireworks festival, the Edo Era confection Isobe Senbei (rice crackers) and ayu (sweetfish) cuisine being the hallmarks of the area.