hot spring good for the skin; beauty bath
Refers to a hot spring or bath whose water is believed to improve skin condition, often advertised at ryokan and onsen resorts.
This inn is reputed to have a hot spring that's good for the skin.
They say your skin becomes smooth after bathing in a beauty hot spring.
美肌の湯 is a similar marketing term for skin-beautifying hot springs, often used interchangeably with 美人湯.
Compound of 美人 (beautiful woman) and 湯 (hot water/bath), referring to a hot spring believed to enhance beauty.