Amanemu Spa

The spa at this remote Aman property in Ise-Shima National Park is fed by actual onsen water, which puts it in a different category from the average hotel wellness floor. Both outdoor pools draw from the same mineral-rich hot springs that the guest rooms do, so the line between spa treatment and just existing here gets pleasantly blurry. Vogue named it among the 100 best spas in the world, and the volcanic seclusion does most of the arguing.