Sol Duc Hot Springs Resort

Sol Duc Hot Springs Resort sits in the Sol Duc River valley inside Olympic National Park, Washington, in temperate rainforest known to local Native tribes for the springs' therapeutic value long before settlers arrived in the 1880s. An elaborate resort opened in 1912, once billed as 'the most noted pleasure and health resort on the Pacific Coast,' burned down in 1916, was rebuilt on a smaller scale in the 1920s, and reopened again after further rebuilding in the 1980s. According to the resort's National Park Service concessioner, the mineral water originates from rain and snowmelt that filters slowly through ancient sedimentary rock and is heated by gases from cooling volcanic formations deep below, emerging into three linked mineral soaking pools kept at roughly 99°F, 101°F and 104°F (37-40°C), alongside a separate unheated freshwater pool ranging 50-85°F (10-30°C).