Namerikawa Onsen
- Location
- Namerikawa, Toyama, Chubu, Japan
- Water type
- bicarbonate
- Temperature
- 40 °C
- pH
- 8
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Soft water — natural, classic buoyancy.
Namerikawa Onsen serves a coastal city on Toyama Bay whose spring beaches host one of Japan's most extraordinary natural phenomena — the nocturnal glowing of hotaru-ika (firefly squid), small cephalopods equipped with photophores that produce brilliant bioluminescent blue light, which gather in the bay in vast numbers between March and May and are carried to the surface by upwelling currents, creating nights when the entire shoreline shimmers with blue-green light from the millions of glowing creatures washing ashore in an event unlike anything visible elsewhere in Japan. The squid are celebrated as a Namerikawa specialty in both their bioluminescent living state and their culinary form — firefly squid with vinegared miso is a signature Toyama dish served in restaurants throughout the prefecture during the season. The onsen's siliceous mineral waters, drawing from the geothermal resources of the Toyama coastal geology, provide warm therapeutic bathing year-round in a city whose most spectacular natural offering appears only for a few weeks each spring when the darkness of Toyama Bay fills with living blue light.