Parque Nacional dos Lençóis Maranhenses offers a unique landscape of vast white sand dunes interspersed with temporary freshwater lagoons, best experienced from June to September when lagoons are full after the rainy season; during the dry season (Oct-Dec), many lagoons dry up. Accessibility requires 4x4 vehicles from towns like Barreirinhas or Santo Amaro, followed by walking on sand, making it challenging for those with mobility issues. Guided tours are highly recommended, often necessary for safe navigation and park access, as solo exploration is difficult and not advised. A typical visit duration is 3-4 days to explore different lagoon circuits and surrounding areas. Costs vary, but expect to budget R$150-R$300+ per person per day for tours, plus accommodation, transport, and food. Essential tips include bringing sunscreen, hats, plenty of water, and comfortable walking sandals, as the sand can get extremely hot. Choosing between Barreirinhas (more developed) and Santo Amaro (closer to core lagoons) depends on preferred travel style.