A resident pod of bottlenose dolphins lives year-round in the Sado estuary, easily watched from boats running out of Setúbal harbour. Several operators (Vertigem Azul, Sado Arrábida) run two- to three-hour trips that combine dolphin spotting with a beach stop on Tróia or in the Arrábida.
Sightings are not guaranteed but are common — the pod is followed daily by researchers, so the skippers know roughly where the animals are. Morning trips are usually calmer than afternoon. Plan around the wind: the estuary gets choppy quickly when the northwesterly nortada picks up.