If you commissioned a designer to come up with a simple, cheap but charming and user-friendly roadside attraction, he or she would do well to create something as good as Phu Sang Waterfall. It’s perfect. Set just to the side of a little frequented, rural highway a clear, shallow stream flows through a picturesque, narrow valley with a lush jungle-clad, limestone outcrop providing a backdrop. The waterfall, originating from a spring higher up the hill, falls directly into the stream and here’s the masterstroke; the water’s hot because it’s a hot spring!