Seiganto-ji (青岸渡寺), Temple of the Blue Waves, is a Tendai Buddhist temple in Wakayama Prefecture, Japan. In 2004, it was listed as a UNESCO World Heritage Site along with other locations, under the name "Sacred Sites and Pilgrimage Routes in the Kii Mountain Range". According to a legend, it was founded by the priest Ragyō Shōnin, a monk from India. The temple was purposely built near Nachi Falls, where it may have previously been a site of nature worship.