This web site is home of the Cabo Rojo Salterns Microbial Observatory. The Cabo Rojo salterns are located in the Southwest region of Puerto Rico and are composed of an estuary, surrounded by natural microbial mats, that feed a series of artificial salt ponds with seawater. The web site introduces the hypersaline environments of Cabo Rojo and includes descriptions of the macroscopic and microscopic life in the region, transmission (TEM) and scanning (SEM) electron microscopy images of the cyanobacterial mats, and information about ongoing research opportunities within the project.