My caving trip with CMRCA was the best thing I did in Chiang Mai! The trip was well- organized, and allows you to see some incredible sights deep in the earth. Cannot say enough about the staff; the trip is led warm, knowledgable and safety oriented instructors who are passionate about the sport. I would highly recommend this trip to anyone, especially those who concerned with spending their money with companies who are socially and environmentally responsible- as this is a far departure from your regular tourist operation. Definitely worth checking out!!