Tróia Peninsula is a huge tongue of fine sand that blocks off the estuary of the Sado, which is hemmed in by dunes and pine woods. Its north and west coasts have undergone a great deal of tourist developments that are disfiguring the landscape, but beyond these areas is the estuary nature reserve: salt marshes, rice paddies and pine groves, which are home to hundreds of species of birds. Some 30 dolphins live in the lagoon.