The Caribbean region coast extends from the Gulf of Uraba to the Gulf of Venezuela and is characterized by a massif plain that extends from the Colombian Andean Mountain range, surrounds the Sierra Nevada de Santa Marta mountain range and covers the Guajira Peninsula to border the Caribbean sea. On the western side of the region there is a relative low altitude mountain range, the Montes de Maria, which is separate from the Andean mountain range. Many rivers cross the Caribbean region, and it contains the CiƩnaga Grande de Santa Marta marsh, one of the biggest in the country.