The cape called El Cap de Sant Antoni has geographical particularities, as it is in a transition zone between areas of sand and cliffs, as well as a particular landscape because it is subject to strong hydrodynamics that indicate a varied underwater topography with various substrates, such as the Posidonia, which make it unique and of great environmental richness.

The huge variety of environments present at Cap de Sant Antoni allows for the emergence of a significant number of benthic communities, some of which are very interesting ecologically and come under the protection rules of the European Council.

The islet called Illot de La Mona is one of the points with the highest density of rare and endemic species in the entire network of flora micro-reserves of the Valencian Community. One can see Silene hifacensis, sea medick and joint pine.

Regarding the seabed of the reserve, the abundant diversity of habitats and species is exceptional. Among them, the highlights are:

• Posidonia meadows, traditionally called “algars”. These are plants with flowers and fruits like terrestrial ones. Posidonia meadows are found only in the Mediterranean, classified as a priority and specially protected habitat. On the northern coast of Dénia, there is a good example: the SCI of L’Almadrava. Important for the production of oxygen, they offer shelter and are breeding grounds for a large number of species. Their presence indicates the good health of the waters. They consolidate the bottoms of the coasts and slow down the transport of sediments and the waves. The accumulation of Posidonia on the beaches protects them from erosion, especially during storms.
• The Alcyonacea forests. At a greater depth, several communities of invertebrate animals (bryozoans, sponges, anemones, etc.) can be found. In the more superficial areas with more light exposure, one can see larger colonial invertebrates that form small forests, such as Leptogorgia sarmentose.
• The sea caves. The calcareous origin of the coast of Dénia allows for the formation of a unique habitat of walls and caves where very little light gets through. In this environment, the rock is covered with invertebrate animals that feed on the organisms carried by the currents. The colours of the animals in the caves (anemones, sponges, ascidians, bryozoans, corals, etc.) are varied and bright, among which some red or calcareous algae can also be found. 

Regarding the caves, Cova Tallà should be highlighted. It was created, on the one hand, naturally, and on the other, artificially, due to the extraction of pumice stone. It is divided into different rooms, some of them dry, where there is neither seawater nor sunlight. In the inner rooms, there are basins that store dripping freshwater. Inside the cave, crucibles from the 11th-12th centuries and an inscription that records the visit of King Felip III in 1599 have been found.

As it is a protected reserve, it is prohibited to anchor boats, do recreational fishing in any of its forms, do sports diving without the corresponding licence, collect marine organisms, marine flora and fauna without the corresponding authorisation, or do nautical sports involving motor boats.