Approximate location — plotted from published sources, not a site visit, and not a guarantee of access.
Historic hot-springs settlement on the Maricopa–Yuma county line north of the Gila River near Hyder. Jesuit Jacobo Sedelmayr recorded Santa Maria del Agua Caliente in 1744; the springs later supported a frontier stage and resort stop after long Indigenous use. Today it is a scant desert historic locale, not a developed public spa—confirm land ownership and avoid trespass.