umi jigoku is small park centered on a cobalt-blue geothermal pool

chinoike jigoku kamado oniishi bozu oniyama shiraike tatsumaki umi beppu hot spring blue boiling coast destination earth famous fog garden geothermal green hell hydrothermal japan kyushu travelling lake landscape national nature oita onsen park pond pool religion sea skin smoke spa steam thermal tourism traditional travel treatment trip water