Lagoa das Sete Cidades

At the western end of São Miguel, the largest island of the Azores, the ground falls away into a caldera roughly six by five kilometres wide, and on its floor lies the biggest body of fresh water in the archipelago. Lagoa das Sete Cidades covers about 4.4 square kilometres and is really one lake pinched in the middle: a shallow channel, crossed by a low bridge, divides a green-tinted basin, Lagoa Verde, from a blue one, Lagoa Azul. The difference in colour, most striking from the rim, comes from the way the two parts reflect light and from their differing ecology. A small village, also called Sete Cidades, sits on the caldera floor beside the water.

The crater is the product of a volcano that is anything but extinct. The Sete Cidades massif collapsed on itself in three major explosive episodes, roughly 36,000, 29,000 and 16,000 years ago, leaving a nested caldera whose walls rise between about 200 and 500 m above the floor. Studies of its deposits count seventeen explosive eruptions inside the caldera in the last five thousand years, which makes it one of the most active centres in the Azores; the pumice cones and maars scattered around the lake, such as the dry crater Caldeira Seca, are the traces of those events. The lake has also paid for its popularity: clearing of forest for pasture from the mid-20th century washed nutrients into the water, and since the late 1980s it has been monitored for algal and cyanobacterial blooms, and warning signs about toxic blooms have been posted along the shore.

Local tradition explains the two colours with a story of a princess with green eyes and a shepherd with blue ones, forbidden to marry, whose tears filled the two lakes when they parted. Other tales connect the lake and its name, "Seven Cities", with the myth of Atlantis. The best-known view is from the Vista do Rei lookout on the southern rim, where both basins lie below at once. From there the waymarked PR03SMI trail runs 7.5 km, linear and graded easy, down the slope of the caldera to the village and its Church of São Nicolau, taking about two hours; the last descent is steep and can be slippery. The lake and its surroundings are classified as a protected landscape.

Getting there

The lake lies about 16.5 km from Ponta Delgada, the island's capital, by straight line and is reached by road. João Paulo II Airport (PDL), the main airport of the Azores, is about 15 km away. A car is the simplest way to combine the rim viewpoints with the village; the colours show best in clear weather.