Mae Sa Waterfall      On the main tourist route of Mae Sa Valley, this multilayered waterfall is great for kodak moments, splashing fun and lazing under cook canopies.      Easily accessible, 45 minutes drive from Chiang Mai and situated in the beautiful Mae Sa Valley where so may other tourist attractions have been established, the Mae Sa Waterfall is one of the most popular picnic spots for residents of Chiang Mai and tourists, both Thai and foreign.      The falls are in a heavily wooded part of the Doi Sutep-Pui National Park. A path winds up for over a mile beside the tumbling cascades and there are many secluded spots off the trail although the whole area can become very crowded at weekends and on public holidays.      A call at the Falls is a memorable end to a day's outing to see elephants at work, to visit orchid, snake and butterfly farms, to have lunch at one of the many resorts and then drive back to Chiang Mai along the precipitous road that twists its way around the back of the Doi Suthep-Pui mountain massif.