The Bahía de Cádiz Natural Park centres on a large area of wetland in the central part of the province's Atlantic coast. Despite high levels of population and development, certain areas have been conserved intact, such as the Sancti Petri Marshes and Trocadero Island, both designated natural areas. Phoenician and Roman remains have been found around these areas, such as the Temple of Hercules on Sancti Petri Island and the old port at Caño del Trocadero, a vestige of trade with the Indies. The strategic and defensive importance of this area had much to do with the appearance, some 3,000 years ago, of human settlements in the bay, leaving behind exceptional heritage with old fortifications.

The intrusion of the sea, the mouths of the Guadalete and San Pedro Rivers, along with the mild Mediterranean climate, determine the ecological characteristics of this wetland and its great diversity of landscapes: beaches, dunes, lakes, marshes and swamps. One of the most interesting ways to discover them is by taking a trip on the Caño de Sancti Petri channel, whether by kayak or sailing boat. There are also other activities such as horse riding routes and diving available at clubs and ports on the coast.

The marshes are the stars of the park and here you will find plants such as saltmeadow cordgrass, salicornia and sarcocornia, according to water levels. The vegetation also invades the dunes, stabilising them as they move further from the coast. Examples of these dune species go from marram grass to Crucianella maritima or pink, sea holly and sea spurge. In the surrounding area there are stone pines and shrubs that survive stoically in the salt-rich soil. Remaining woodland such as the Algaida Pine Wood gives an idea of the dense pine forest that used to run between El Puerto de Santa María and Puerto Real. This is home to the chameleon, which is an endangered species.

Its position between the Doñana and and Estrecho Natural Parks make it a privileged setting to observe the birds that migrate between Europe and Africa. This is home to some of Spain's largest colonies of little tern, black-winged stilt and avocet. On the beaches you can see northern gannet, cormorant, yellow-legged gull and waders such as oystercatchers, as well as sanderling, bar-tailed godwit, little tern and Kentish plover. Other residents are the elegant flamingo and the osprey.

The lives of many inhabitants of this area have centred around its salt pans, conditioning their subsistence since time immemorial and marking their character. A walk around its trails will show you their influence on the landscape, with the "Casas Salineras" (Salt-making houses) and the Arillo River salt pans. At the same time you can see a host of different birds from the specific ornithological observatories.

Nowadays, salt extraction has made way for other activities such as marsh shellfish collecting, shallow-water fishing and the booming fish farming trade, the area's main resources. Here you can sample local king prawns, clams, oysters, sea bass, sole, mullet and marsh-farmed sea bass, all renowned for their quality. Shrimp omelettes (fritters) are also famous, made with chickpea flower (once ground in local tidal mills, some of which can be seen to this day) and all washed down with local wines.