Ñireco Canyon's notorious rapids, Jugbuster, Milky Way, Lost Yak, Lava South, Cyclops and Last Laugh, have a legendary reputation in the whitewater rafting community. Technical, big, and bouncy, these rapids have humbled the best guides in the world. Kayakers love this run, especially when high flows transform the Bío into one of the best big water runsanywhere.

Unicorn is the wake up call after departing from Quepuca. The first big rapid, Jugbuster, looms a kilometer downstream below a suspension bridge. It changed dramatically in 1991 due to a huge landslide that originated from high on the left wall. Although short, this tumultuous drop requires caution due to shallow, sharp rocks. A few hundred meters below Jugbuster is the proposed Ralco Dam site. In part through the tireless efforts of lawyer Fernando Dougnac and Juan Pablo Orrego at GABB (Grupo de Acción por el Bío-Bío), this project has been forestalled. If built, the dam will flood the largest area of the six proposed dams, and inflict the greatest havoc on native flora and fauna, and the Mapuche-Pehuenche Indians. Water diverted into a tube will bypass the entire canyon, not returning to the channel until 11 km downstream at a condo-sized block of basalt known as Heartbreak Hotel. Inundated areas upstream would include the lower Río Lomín, Baños de Lolco, and Quepuca.

Milky Way, named after the tributary Río Malla's glacial torrent, contains a long series of ledge holes and breaking waves. Rafts run from right center at the top to far right at the bottom. Ejected flotsam can be safely recovered in the large pool below the rapid. From this point, the gradient steepens dramatically as you enter the heart of Ñireco.

Rafters should get out directly from the magnificent and often photographed Rio Ñireco waterfall to scout Lost Yak, an all-time classic rapid. For a large margin of safety at extremely high flows, run Lost Yak right of the island. Technically it is the toughest rapid on the river, especially at medium-to-low water where a swim through the rocks on the right could get ugly. Sneaking the left side through a maze of rocks is possible, but most guides run down the center. A flip can spell disaster if people and gear are not quickly brought to shore because continuous class III-IV rapids lead directly into Lava South downstream.

First timers should walk all the way down to scout Lava South (~700m) prior to running Lost Yak. High water runs are commonly down the right through a rock sieve known as the Pickett Fence. Medium-to-low flows allow for a run against the left wall through the huge hole and notorious Whale's Tail immediately downstream. The combination of Lost Yak and Lava South present one of the world's ultimate rafting challenges. All safety precautions should be taken to avoid disaster. In the event of a late afternoon ordeal, it is possible to camp on the rocky terrace at the bottom of Lava South on the left.

A couple hundred meters of flatwater separate Lava South from the next big drop, Cyclops. The river crashes into a vertical wall, rebounding with tube-sucking hydraulics as it makes an abrupt turn to the right. Below Cyclops, an unnamed class IV rapid separates it from the appropriately named Last Laugh. Long and powerful, this rapid is usually run on the left, although at extremely high flows rafts can sneak by at the bottom through a slot on the far right. Scout right for a view of the huge pour over in the center of the river. It's big fun getting obliterated on the left by the largest standing wave on the river! A few smaller, playful rapids follow before the welcome sight of Heartbreak Hotel.

Hiking up to a primeval araucaria forest in the upper Río Malla drainage takes approximately four hours. A base camp in the trees serves an overnight bivouac for summit attempts on Volcán Callaqui (3050 m). Steaming fumaroles, sulfur deposits and recent lava flows attest to the potential seismicity of this volcano located only 5 km away as the condor flies from Pangue Dam. Climbing the volcano involves scree slope scrambling, and mixed snow and ice trekking on a 30 degree slope. Bring crampons early in the season as well as a pair of nylon pants for the return glissade. This strenuous trek requires a day and half round-trip from the river.

For general directions, refer to the lower Bío-Bío description. The shuttle road from Heartbreak Hotel upstream to Quepuca allows for expansive views of the canyon below. After descending to river, look for a large soccer field known as Quepuca. Heartbreak Hotel is located 15 km downstream where the road winds down to Jose's pasture. A local bus climbs the road from Ralco to Lepoy during weekdays arriving at Quepuca around 1800 hours. It's a good time listening to the driver's banter with the locals while bouncing down the road.