White dunes filled with blue rainwater lagoons
Lençóis Maranhenses National Park looks like a desert but gets heavy rain in the first half of the year, which pools in the hollows between its dunes. From around June to September, the lagoons are at their fullest and warm enough for swimming, in blue and green water stretching to the horizon. Barreirinhas is the main base, with 4x4 trips out to Lagoa Azul and Lagoa Bonita, and boat rides down the Preguiças River to the coast. Multi-day treks cross the dunes, staying in fishing villages.