Colonia Glacier, Valley glacier in Northern Patagonian Ice Field, Chile

Colonia Glacier is a valley glacier in the Northern Patagonian Ice Field, spilling southeast from an ice plateau north of Cerro Arenales. Its terminus lies about 4 km from Colonia Lake, and the ice dams both Cachet II and Arco lakes.

Colonia Glacier dams two lakes, Cachet II and Arco Lake, and the ice wall holding Cachet II fails repeatedly, producing outburst floods. Since 2008 the lake has drained eleven times. On 31 March 2012, its second emptying that year, nearly all of its 200 million cubic metres of water disappeared in under 24 hours through perforations in the ice, a process linked to rising temperatures.

Since 2008 the ice dam holding Lake Cachet II has failed eleven times, and each rupture drains roughly 200 million cubic meters of water within about 24 hours. The lake emptied twice in 2012, the second time on 31 March. Researchers link the growing frequency of these outburst floods to rising temperatures, making the glacier a monitored site for watching climate-driven change in the Northern Patagonian Ice Field.

The glacier ends about 4 km (2.5 mi) from Colonia Lake, so the ice front is viewed from a distance rather than reached on foot. The ice dam holding back Cachet II can fail, and the lake has drained 11 times since 2008; check current conditions before travelling. Plan for remote roads and changeable weather.

The glacier creates natural dams for two lakes, including one that drains completely through small perforations in the ice wall within just a few hours. This rapid drainage cycle is a rare geological event that repeats on a regular basis.