Barreirinhas is the seat of the municipality and through which most of the travelers who come to visit the region arrive. It is the main entry point for the Lençóis Maranhenses. With a population of approximately 60,000 inhabitants, it was founded in 1871 and emancipated in 1938. Its economy is based on small farming, fishing and tourism. It is located 260 km from the state capital, São Luís, from where you arrive at approximately 3:00 a.m. to 3:30 p.m. by car or 4:00 a.m. in Vans and 4:30 a.m. by 5:00 p.m. by conventional bus leaving from the bus station of São Luís.

In Barreirinhas there are a large number of pousadas and some restaurants. All the commerce of the region concentrates there, pharmacies, minimarkets, public market, bakeries, stationary, stores of material of construction, etc. There are only three banks operating in the city, Banco do Brasil, Caixa Econômica Federal and Bradesco. There are no money exchange offices, only Banco do Brasil does this type of operation in the city. In Barreirinhas there is also a reasonably equipped hospital, which guarantees the first basic services, first and second grade schools, a college, police station, churches and the building of the City Hall and municipal secretariats.

From Barreirinhas depart the vehicles 4X4 and the voadeiras (aluminum boats) that take the visitors to the most diverse tours in the region. From here you get access to the Atins de voadeira or 4×4 vehicle, but be warned, you should book this transfer in advance, otherwise you may not find transportation available at the time of your arrival or have to charter one exclusively for your trip, which will come much more expensive than the conventional ride or line.