Cotopaxi is the world’s second highest active volcano and, at 5,897m, the second-highest summit in Ecuador. It is also one of the world’s most active volcanoes. Cotopaxi means “Neck of the Moon”. The mountain was worshipped by local Andean people as a place where rains originated, and as a major supply of water, before even the Inca people arrived in Ecuador in the 15th century. On 14th August 2015, an eruption of ash and steam issued from Cotopaxi, one of 100 or so eruptions that have taken place in the last 500 years. Like several of the Colombian 25zero mountains, eruptions on Cotopaxi are a major threat to the local people, as they risk triggering a lahar or mudslide caused by the volcano’s heat melting vast sections of glacier quickly. A large lahar generated by an eruption in 1877 travelled over 300km to the Pacific coast. A similar flow today along the path it took – the Valle de Los Chillos – would be devastating to the 200,000 people who now live there. Cotopaxi’s glaciers and their meltwater, therefore, are both lifeblood and feared nemesis for cities and farmers; their waters sustain their lives and livelihoods, yet a lahar resulting from the too-rapid melting caused by an eruption would spell disaster.