Brazil’s shimmering Sand Dune Lagoons (Lencois Maranhenses National Park)

Lençóis Maranhenses National Park

Brazil’s shimmering lagoons are no mirage

Seen from the air, the sweeping white dunes at Lencois Maranhenses National Park in Brazil resemble tousled bedsheets, giving this natural wonder its unusual name – the Bedsheets of Maranhao.

But unlike most deserts in the world, for a few months every year, seasonal rains transform this windswept terrain into a mysterious landscape of flat, shimmering pools curled against the contours of sun-bleached hills. (The precipitation means Lencois is not a true desert.)

As much as 150 centimetres of rainfall leave behind hundreds of these shallow, freshwater lagoons – all but a few of them will gradually disappear again – throughout a vast area extending for more than 1,500 square kilometres.

“I’ve travelled to a lot of amazing places, both in Brazil and abroad,” says Affonso Araujo, a university professor from Rio de Janeiro, Brazil, who recently visited the site with his wife, Shirley Furtado. “But in terms of natural beauty, it is difficult to find anything else like this. It looks like a desert but in the middle of the dunes there are the lagoons. It is just remarkable.”

“Dazzling,” Ms. Furtado adds.

Wedged against the Atlantic coast of the state of Maranhao next to the Preguicas River, the Lencois Maranhenses National Park is an officially protected area where motor vehicles are not allowed. Cyclists and trekkers are welcome, however, and guided tours are, while not obligatory, a good idea. The area is so large, it is possible to get lost.

The best time to visit the park is between the months of May and September, when the rains have stopped and the lagoons are their fullest. From the ground, visitors will see sharp-edged sand dunes rearing like icebergs from the expanses of gently rippling water. Schools of fish swim in brilliant pools, born from eggs dropped by passing seabirds, according to some locals. Two small communities are permitted to live in the park and their herds of lean, coffee-coloured goats may be seen roaming the landscape.

For Araujo, however, swimming in a lake among the towering white dunes was the biggest highlight. “The water isn’t salty,” he points out. “It’s fresh water, crystal clear, full of little fish and, on the days that we were there, the temperature was perfect. It was unbelievable.”

As its fame starts to spread, the Lencois Maranhenses is attracting increasing numbers of visitors, and tour operators are beginning to include it among Brazil’s many other attractions in their travel packages. Yet it remains one of the world’s lesser-known natural wonders, a geographic anomaly that is constantly shifting.