The most eco-friendly and natural hot springs in La Fortuna is called Termalitas Del Arenal and it only costs 9 colones.

The Termalitas del Arenal hot spring is located in the Arenal Volcano area of Costa Rica. This geothermally-heated pool complex is one of the main attractions of the La Fortuna region. It offers an array of amenities to make your day of relaxation perfect, including a sweeping view of the volcano and lush rainforest landscapes, hydrotherapy systems, a shallow cave pool, 8 different hot springs with temperatures ranging from 103-113°F (39-45°C) and a children's area where kids can splash about safely. There are also restaurants on-site offering delicious local and international cuisine. The atmosphere at Termalitas del Arenal hot spring is tranquil, relaxing and inviting - the perfect place to chill out and soak up the natural beauty of Costa Rica.