This basin also encompasses the Ciénaga Grande de Santa Marta, the largest marsh in the north of the country, which is formed by 16 smaller marshes that are connected by means of arms within the march. The balance of the march is a delicate one that depends on the fresh waters coming from the Sierra Nevada, and the periodical flooding of the Magdalena River, and the salt water coming from the mouth of the March to the sea, that is carried by the current and winds into the marshland.