There are several hot springs in Arenal, but the hot springs accessible via The Tabacon Resort are the most rewarding!
Visit the hot springs at The Tabacon and you can walk a maze of paths all along the streams and pools of hot springs, and hop in whenever and wherever you please. For adults, there is a private bar area, called Shangri-La, tucked high up into the meandering hot springs' paths that you may stumble upon. Go there to jump into the springs, be surrounded by rainforest and mist, and be brought a glass of vino by a delightful bartender while at it. Not too shabby!