garden open-air bath
An outdoor hot spring bath set within a garden, often at a ryokan or onsen facility.
The garden open-air bath at this inn lets you enjoy the scenery of each season.
露天風呂 is a general open-air bath, while 庭園露天風呂 specifically refers to one situated in a garden.
Compound of 庭園 (garden) + 露天風呂 (open-air bath).