Recognizing the insufficient protection conferred on the area, Decree 622/76 was passed on 28 July 1976, creating the Parque Natural da Arrábida (PNArr).

The park is named for the main geomorphological unit that covers the entire area, designated the Arrábida cordillera or massif, consisting of three subareas:[5] This group is oriented east-northeast to west-southwest, covering an area of about 35 kilometres (22 mi) long and 6 kilometres (3.7 mi) wide, and reaching 501 metres (1,644 ft) at its highest altitude as a result of the Formosinho anticline.

Over the sea and abrupt cliffs are the Serra do Risco and Píncaro, the highest point along the Portuguese coast in this area, at approximately 380 metres (1,250 ft).

From a paleontological perspective there are fossil deposits that include fragments of dinosaurs (normally sauropods), relevant to scientific investigation, commonly associated with Cape Espichel.

The coast, generally elevated and abrupt, is 380 metres (1,250 ft) at the Alto do Píncaro, with rare and small beaches and coves, mostly accessible by boat.

[6] From Alpertuche to Outão the coast is less elevated resulting in more beaches, such as the bay of Portinho or Chã da Anixa, a small platform only metres above the sea.

The humid air masses that come from the Atlantic in the cooler months are confronted by the rugged mountains resulting in abundant precipitation in November and December.

In the summer, some upwelling occurs around Cabo Espichel which decreases sea temperature and increases the frequency of fogs, which are usually only present in the morning or late in the day.

The complexity and diversity of marine habitats present in the waters of Arrábida have contributed to it being a hotspot of biodiversity, with 1400 registered species occupying the space.

[9] Arrábida is depicted in the video game Tom Clancy's Endwar as one of the theatres in World War III, when the U.S. Army invades Portugal in an attempt to weaken the European Federation's defences.