Lago de Coatepeque: the lake that changes colour

Coatepeque is what remains after a volcano collapsed into its own emptied magma chamber. The caldera is roughly 25 km² and the water reaches about 115 m deep, ringed by steep green walls that make the whole thing feel considerably more remote than an hour from San Salvador.

The colour

Every so often the lake turns an implausible milky turquoise — the kind of colour that makes photographs look edited. It is caused by a phytoplankton bloom, and the practical thing to know is that nobody can tell you when it will happen. It tends to be reported during the dry season, it can last days or weeks, and plenty of visitors go their whole trip without seeing it.

Treat it as a bonus. On any ordinary day the lake is deep blue and the setting alone justifies the drive.

Getting on the water

Small boats run out to Isla Teopán, the island near the middle, and most shoreline operators will take you round the caldera wall for an hour. Agree the price before you get in — rates are negotiable and are not posted anywhere.

Swimming is straightforward. The water is clean and warmer than you expect, and most of the lakeside restaurants have a dock or a ladder you can use if you eat there.

Eating

The lakeside comedores do fried tilapia whole, with plantain and rice. Sit close enough to the water and it is one of the better lunches in the country for the money. Most places on the shore are effectively private, so access usually comes with a minimum spend — reasonable, and worth it for the setting.

Doing it with Cerro Verde

The two are close and pair naturally: Cerro Verde in the morning while the view is clear, Coatepeque in the afternoon for lunch and a swim. That is a very good day in western El Salvador, and it is entirely doable as a round trip from Santa Tecla.