noun
waterfall shower; pelting water stream
Refers to a bathing facility where hot spring water falls from a height onto the bather's back or shoulders, providing a massaging effect. Common in onsen and sento.
この温泉には打たせ湯があって、肩こりに効くそうです。
This hot spring has a waterfall shower, and it's said to be good for stiff shoulders.
打たせ湯の勢いが強くて、最初はびっくりした。
The force of the waterfall shower was so strong that I was surprised at first.
温泉 is a hot spring in general, while 打たせ湯 specifically refers to a waterfall-like shower facility within a hot spring.
ジャグジー is a jacuzzi with bubbling water, whereas 打たせ湯 uses falling water for massage.
Compound of 打たせ (causative stem of 打つ 'to strike') + 湯 'hot water'. Literally 'water that makes one strike', referring to the percussive effect of the falling water.