The Estuário do Sado is one of the few places in the world that a pod of dolphins actively lives within a freshwater estuary. The pod of approximately 28 bottlenose dolphins is routinely spotted swimming, hunting or playing in the waters south of Setubal. One of the more popular activities while in Setubal or Troia is to join a half day dolphin watching trip and tour of the Reserva Natural do Estuário do Sado.

As the Sado estuary is a relatively small body of water, there is a very high chance of spotting a dolphin, and certain tour companies boast a 95% spotting rate.

There will be dredging works on Sado River, and that unleashed series of discussions and studies that the overall population highly disagrees.