During high tide the sea flows between the islands in the western side and, blocked by the beach it fills the lagoon between the sandy area and the rocks.

The land is mountainous with rough, nearly vertical cliffs of more than 100 m (328 ft) on the western side, and numerous caves (furnas) formed by erosion from the sea and the wind.

The eastern side is less steep, covered by woods and bushes and protected from the Atlantic winds, allowing the formation of beaches and dunes.

The level of legal protection varied until November 21, 2000, when the Galician Parliament unanimously agreed to apply for the status of National Park to the central Government.

National Parks are nature areas nearly untransformed by human activity that, based on their landscape, geological or ecosystems possess aesthetic, ecologic, educative or scientific values worth of special protection.

"Galegos come here to spend long, lazy summer days on the Praia das Rodas, a perfect crescent of soft, pale sand backed by small dunes sheltering a calm lagoon of crystal-clear sea", says the magazine.

In 2022, the island was chosen by the New York Times, as one of the 52 Places for a Changed World, due to its efforts "to protect its environment and guard against overtourism".

[3] The scrubland is formed mainly of autochthonous species, like gorse, broom, asparagus, spurge flax (Thymelaea) or rockrose (Cistaceae).

The woodland has suffered bigger alterations, since most native species like the common fig or the pyrenaean oak (Quercus pyrenaica) are now reduced to symbolic representation by the reforestation of nearly one fourth of the surface with pine trees and eucalyptus.

Some rare and representative coastal species do grow in the dunes, beaches and cliffs under very extreme climatic conditions, as the sea pink (Armeria pungens; in galician herba de namorar or "love plant"), locally endangered, and an important number of camariñas (galician common name for Corema album), an endemic species from the Iberian Peninsula western coast.