Termales del Bosque is a hot spring complex about 20 minutes east of Ciudad Quesada, significantly less crowded and expensive than the resort pools near La Fortuna and Arenal. Several thermal pools of varying temperatures sit within a wooded setting, with a cold river nearby for alternating dips. The surrounding forest is birder territory — the area around Juan Castro Blanco National Park is one of the better places in Costa Rica for cloud forest species.
Access requires a car or taxi from Ciudad Quesada. Admission is charged but well below Arenal-area prices. The complex has changing rooms and basic food service. Arrive early to have the pools mostly to yourself.