The Rio Laja rips through a geologic wonderland Upstream from Salto del Laja, a popular roadside attraction along the Pan American highway. Draining Laguna del Laja, this scintillating gem features kick-ass, heart-thumping action from start to finish. The first 200 m are the toughest and should be scouted. Only run the Laja if you have a bombproof roll. In fact, don't even think about tipping over. The razor-sharp basalt will shred you and your equipment if you find yourself upside down. Walking along the shore is impossible due to the vegetation and channels of swift water. Repeat runs are a blast, with three to four descents a day not uncommon.

Sierra Velluda (3585 m) and Volcán Antuco (2979 m) dominate the southern horizon. In 1853, vicous lava flows from the eruption of Antuco oozed over the valley floor, plugged the river and caused the water level in Laguna del Laja to rise 20 m. Groundwater percolates through this porous basalt, bursting out of the canyon walls at the nacimiento, or the birthplace of the river. The effervescent water flowing from this Garden of Eden is cold and crystal clear.

From Los Angeles, 518 km south of Santiago, drive east towards the town of Antuco and Parque Nacional Laguna del Laja. Oncoming cars used to challenge us with a game of "chicken", waiting until the last possible moment to swerve off the only paved lane into billowy clouds of dust. That thrill is gone now that both lanes are paved. So much for progress. After entering the park, drive 4 km up the hill to an obscure photo-op sign and an eroded concrete foundation. Turn left and continue 300 m to the trailhead. Hike down the trail 20 minutes towards the gushing cascade. When you reach the rim of the canyon,

continue downriver another 100 m to switchbacks that lead to the water's edge. Take out in the meadow next to the ENDESA reservoir. Below the reservoir, the gradient looks steep, but far from deep. In fact, it's bone dry in the summer. Why isn't a minimum year-round stream flow maintained for fisheries and recreation?