Bua Tong waterfall (The Rainbow or Seven Colors Spring) is located north of Chiang Mai. The water source for Bua Tong waterfall is the Rainbow or Seven Colors Spring. The spring water contains a high amount of calcium carbonate. As the spring water cascades down the falls, the calcium is deposited on the rocks. The calcium carbonate then adds a non-slip surface to the rocks. Believe it or not, the rocks look slick but it is very easy to walk up the face of the falls without slipping. It is almost as if someone decided to pour cement down over the rocks and it hardened under the water. This single feature makes it a worthwhile visit to Bua Tong waterfall. However, don't go just for the falls, go for the beauty of the forest as well.