The municipality of Olhão, situated in the Eastern Algarve/algarvian Leeward, is one of the 16 municipalities in the district of Faro, with an approximate land area of 130km2, distributed by 5 parishes: Olhão, Fuseta, Moncarapacho, Pechão and Quelfes, with a population of 45,396 inhabitants ( census 2011), which corresponds to a population density of 346.83 hab./km².
It makes frontier in the east and in the north with the municipality of Tavira, in the west with the municipality of Faro and in the south it's bounded by the Atlantic Ocean, the Olhão municipality is part of the morphological sub-regions of the Barrocal (Lower Algarve) and the littoral. In the Barrocal (Lower Algarve), the Olhão municipality is limited in the north by the old massive contact line and in the south by the limestones dated from the Mesozoic Era. This contact line represents an ancient coastline, that's why, the existence of sedimentary deposits (limestones/calcareous region) over those of the old massif.
The coastline is the sub-region with the most recent deposit materials, the Quaternary or even the Neogene eras. These deposits came over the limestone and marl that constitutes the Meridional Mesocenozoica Edge, presenting by its "youth", an irregular relief supported by a platform still a little bit shredded by a superficial outflow.
The entire coastal area of Olhão municipality is part of the Ria Formosa Natural Park, one of the most important wetlands at an European level, having been considered in 2004 by the International Union for Conservation of Nature, as a wetland of worldwide interest.
The Ria Formosa Natural Park instituded in 1987 by the Law-Decree No. 373/87, on the 9th of December, was founded with the main aim to protect and preserve the lagoon system,, namely, its flora and fauna, including the migratory species and their habitats.
It stretches through the municipalities of Loulé, Faro, Olhão, Tavira and Vila Real de Santo António, and covers an area of about 18,400 hectares along 60 km of coastline, from Ancão to Manta Rota, including a wide range of habitats: the barrier islands, marshes, mud flats and sand dunes, salt marshes, freshwater ponds and brackish, waterways, agricultural areas and forests.
In the municipality of Olhão, the Armona Island is part of the barrier islands system of Ria Formosa, where we stand out the beaches of Fuseta Mar and Armona Mar.