Let's Relax Spa : Thonglor Spend time relaxing with spa and onsen massages in the heart of Thonglor. Experience the ultimate relaxation experience. Slowly pass the time while providing relaxation to let the body experience true peace with the best of two Asian disciplines. Discover Bangkok's onsen here, Let's Relax Onsen & Spa, the first full-service spa. on an area of more than 1,800 square meters in the heart of Bangkok where you will experience the spirit of peace By soaking in the onsen in the Sukhumvit-Thonglor area with leading spa packages that comes with a spa massage with authentic Thai fresh herbs."