Located in the state of Goiás, the São Marcos River forms the boundary between the municipalities of Catalão and Campo Alegre. This area was once home to several farms, all belonging to members of the same family. Of some of these farms, only ruins remain, persistent reminders that, at one time, people lived there. The few inhabitants who have stayed are, day by day, losing more ground to large-scale soybean plantations and the reservoir created by the Serra do Facão Hydroelectric Power Plant. "Mar Verde" explores the routines and daily lives of these people.