into the blue

In the northern reaches of Brazil, the unique and fragile landscapes of the Lençóis reward the adventurous.

- Michael Snyder

LIKE MOST ANYONE who lives in the oases at the heart of Brazil's Lençóis Maranhenses National Park, a sprawling field of bone-white sand dunes and cerulean lagoons, Cassio José França Souza can identify his friends and family by their footprints. Souza, who grew up in the riverside fishing village of Santo Amaro do Maranhão, just outside the park, leaves singular tracks in the talcum-soft sand, with big toes that hang off the front of his sandals. His wife's prints, he told me with an affectionate grin, one dazzling morning in June, are "small and round."

Though Souza first guided visitors into the park 15 years ago, when he was still a teenager, it was his wife who grew up among these dunes, in an oasis known as Baixa Grande. "Everything I know, I learned from her, and she learned everything she knows from growing up here," Souza told me as we walked past amphitheaters of sand and parabolas of water painted onto a cyclorama sky. Her name, he told me, was borderline biblical: Maria dos Milagres, or Maria of Miracles.