City-run thermal park in Federación, Entre Ríos, with multiple pools and an adjacent water park. Open daily (posted 08:00 to 20:00); minors need an adult.

Mountain hot springs and a spa hotel in Termas de Reyes, Jujuy, in the Yungas foothills near San Salvador de Jujuy. Bring layers for chilly nights.

Large thermal resort park near Villa Elisa, Entre Ríos, with 10 pools across 41 hectares plus lodging, spa, and a lake. Good for long, low-key days.

A terraced complex of 14 thermal pools above Fiambalá, Catamarca, known for hot and cooler options. Cash and supplies matter out here. Bring water.

Thermal pools and a water park beside the Mendoza River, 39 km from Mendoza City, day passes and an adults-only spa area (14+). Bring sandals, towel.

Seasonal geothermal baths and mud at Copahue Volcano, 19 km from Caviahue, typically Dec to Apr. Entry requires an intake form, due to snow.