Cuicocha, which means “guinea pig lake” in Qechua, is a crater lake situated at the foot of Cotocachi Volcano, at an altitude of 3200 m. Emerging from the dark waters of the 3 kilometer wide lake are four spectacularly perfect vegetation-covered domes which were formed by the last eruption over 3,000 years ago. Boats, which depart every half hour or so, will take you around the islands, near which you can observe bubbles of sulfur gas escaping to the surface and turning the water lukewarm. The ride costs about $2 and includes a voucher for a free canelazo at the cafeteria. If you are up for a three-to-four hour hike, you can also follow the path along the rim of the crater, which offers spectacular views of the surrounding volcanoes and of Otavalo valley.