Lagoa de Óbidos, in the district of Caldas da Rainha, is the biggest lagoon system of Portugal. It is an area of rich biodiversity that was and still is crucial for the development of the nearby towns. Records seem to show that, centuries ago, it actually spread all the way to the village of Óbidos, from where it gets its name. The estuary of several rivers, it sits on a shallow depression in the land, near the sea, forming an ever-changing silhouette at the point where its waters meet with the ocean. Its natural beauty and lush habitat offer a fantastic scenery for the beaches of Foz do Arelho and Bom Sucesso, for birdwatching, hiking, watersports, and simply enjoying its sights.