First some facts about QuilotoaIt is a water-filled caldera and the most western volcano in the Ecuadorian Andes. The 3 kilometres wide caldera was formed by the collapse of this dacite volcano following a catastrophic eruption about 800 years ago. The caldera has since accumulated a 250 m (820 ft) deep crater lake, which has a greenish color as a result of dissolved minerals. Fumaroles are found on the lake floor and hot springs occur on the eastern flank of the volcano. Thanks Wikipedia!
Quilotoa is a tourist site of growing popularity. It's a half-hour hike down from the viewpoint (and 1-2 hour hike back up the 280-meter vertical ascent).
Also it is possible to rent a horse or a donkey for the hike, just in case that the altitude is affecting you too much.