The park was created in 1981 with an initial area of 155,000 hectares.

The shifting dunes with the lakes in between are most spectacular at low sun, when a range of shadows come into play. Just after sunrise is probably thev very best because of lower temperatures. Besides the vast sand dunes, the park includes two oases, known as restingas and has areas of mangrove swamps along 70 km of coastline and wetlands along the Parnaíba River.

At first glance, the dry sands don't seem to cater for much, but look deeper and you'll find more biodiversity than you might expect. Although the lakes and ponds are seasonal, some tiny fish can be found there, more than 120 species of bird are found in the park. Look for them in bushes along the rim of the dunes, and near the oases and mangroves. There are also birds that manage to carve a niche for themselves in the seemingly barren sand dunes, where at least 40 reptile species are known to thrive. Human presence leaves its mark on the park as well and quite a few cattle and goats can be seen grazing along the lakes.

The park is home to four endangered species: the scarlet ibis, the neotropical otter, the oncilla, and the West Indian manatee.

Best time to visit is May - September, after the rains, and before the lakes dry out. The almost constant breeze may fool you into thinking the sun is not getting at you. Think again!

Most people sleep in Barreirinhas and do daytrips. However, the dunes are far more accessible if you stay in Atins, or even better in Canto de Atins. Mandacaru and Caburé are less convenient alternatives. Paulino Neves offers proximity to similar sights (Pequenos Lençóis), although not inside the actual national park. There is also the little explored town of Santo Amaro on the park´s western rim. Guided treks are available. There are a number of trekking options with Lencois Maranhenses and guides are highly recommended. Lodging is available from locals who live in two oasis' within the park. Sleeping in hammocks and meals of rice, beans and chicken are the norm.

No restrictions so far, but there is some talking, due to garbage left behind. Do your part and pack out anything you bring in!

Making short distance day trips inside the park do not deliver the cultural experience or the solitude Lencois Maranhenses can provide. Surprisingly, the dunes are well-packed from seasonal rains and much easier to walk on than typical beach sand.