This is one of the thermal waters lagoons in Cuatro Cienegas valley in the northern Mexican state of Coahuila. Water temperature in this place is extremely constant around the year, with just variations of 0.5° Celsius from 34.5° Celsius. This place has a bottom of rocks, gypsum silt and also deep layers of detritus and holds completely transparent water. pH is on the alkaline side near 7.8 and water hardness is very high. This is a small spring and just holds part of the fish fauna of Cuatro Cienegas de Carranza, not all of the species. It is one of the few places however where the piscivorous morph of the Cuatro Cienegas cichlids, Herichthys minckleyi is found. No plants are available in the water but just overhanging grass around in the edges. The spring is 4.5 meters deep. (26.923469°N, 102.122503°W). Photo by Juan Miguel Artigas Azas.