Apacheta de Irpa o Cancosa Pass
Paso Apacheta de Irpa o Cancosa is an international high mountain pass at an elevation of 4.010m (13,156ft) above the sea level, located on the border of Chile and Bolivia.
The road over the pass is gravel. The climb is simply terrible, with a notorius lack of oxygen that tests the organisms and a high degree of steepness. Most people feel altitude sickness at around 2,500-2,800 meters. This track can get very muddy and slippery after rain making it challenging to get through. The border is open from 8 am to 6pm. Open to all motorized vehicles, however, strongly recommended for high clearance, 4-wheel drive vehicles. The road is very rough--only try driving it in a 2wd car, if you're planning to buy a new car.
Pic: Aylton Baffa