The “High Dune” is about 650 feet high. 
In General:


Entrance fees are $25 7-day pass.
Plan to hike on the dunes in morning or evening to avoid afternoon storms, and to avoid the hot mid-day sand surface.
The Black Canyon is so named on account of its steepness. As a result, the canyon walls are most often in shadow, causing the rocky walls to appear black. At its narrowest point the canyon is only 40 ft across at the river and 1100 ft at the rim. The Painted Wall is the highest cliff in Colorado. From river to rim it stands at 2250 feet.
This route heads south from US 50 and follows along the Lake Fork of the Gunnison River into Lake City. It then climbs up and over Spring Creek Pass and shadows the upper reaches of the Rio Grande to its end at the junction with US160 in South Fork.