Freshwater from the peninsula's extensive aquifer has an outlet in the reserve, mixing with the salt waters of the Gulf of Mexico in the wetlands.

[3] The reserve is home to large and diverse populations of migratory and resident birds, with over 304 species identified.

[4] American flamingoes (Phoenicopterus ruber) are a prominent species, with a population that can reach over 23,000 birds.

Other bird species present here include the plumbeous kite (Ictinia plumbea) brant goose (Branta bernicla), Muscovy duck (Cairina moschata), piping plover (Charadrius melodus), ocellated turkey (Agriocharis ocellata), Yucatan poorwill (Nyctiphrynus yucatanicus), Yucatan wren (Campylorhynchus yucatanicus), Yucatan jay (Cyanocorax yucatanicus), and orange oriole (Icterus auratus).

[2] In 2008 the Mexican government nominated the Ría Celestún and adjacent Los Petenes reserves as a World Heritage Site.