Located in the municipality of Cockaigne-Lucena is easily accessible by road from Cockaigne with Lucena. Ranked 13 hectares of natural reserve and 250 protection zone, is characterized by the presence of birds such as white-headed ducks, the little grebe, the wigeon, Shoveler, pato colorado, calamón, pochard and tufted, etc..
This lake is fed by rainwater and runoff. The high concentration of sulphate magnesium waters possessing endow the bitter that gives name to this gap.
It is said that a carrier carrying a cart with two oxen near the lagoon, they were startled to see a snake, stampeded and fell to the lagoon, can not be rescued, ni bueyes ni carro, because of its large depth. Now, the lagoon, is a closed space with priority given to the protection, research and the educational aspect (cultural visits) and sports (hiking).
It is adjacent to the Laguna Amarga, this is shallow and temporary, Coming to dry in summer as it feeds mainly on rainwater. Among the fauna, we can find the grebe, laughing gull, Heron, garcilla boheyera, etc ...