Tres Vírgenes, Stratovolcano in Mulegé, Mexico

Tres Vírgenes is a volcanic complex in Mulegé, Baja California Sur, made up of three northeast–southwest aligned volcanoes: El Viejo, El Azufre and El Vírgen. El Vírgen, the youngest and most conspicuous, is commonly called Las Tres Vírgenes. The complex includes lava domes, scoria cones and andesitic to dacitic flows; El Vírgen alone has at least six scoria cones and four lava domes.

The volcanic complex was documented by Croatian Jesuit missionary Ferdinand Konščak in 1746, who recorded an eruption on his map. This historical record demonstrates that volcanic activity here was observable in the early 18th century and caught the attention of early explorers.

The name Las Tres Vírgenes, "the three virgins", is commonly applied to El Vírgen alone, the most conspicuous of the three cones; the other two are El Viejo to the northeast and El Azufre in the middle. The three volcanoes are aligned northeast to southwest, and the complex belongs to a volcanic ridge running from Baja California toward the Guaymas Basin.

The complex lies in the Gulf of California rift zone, where offshore volcanic ridges run from Tres Vírgenes–Aguajito–La Reforma toward the Guaymas Basin spreading centers. The three cones are aligned northeast to southwest: El Viejo, El Azufre and El Vírgen. The ground beneath the lavas is Cretaceous granite, topped by the Santa Rosalía Formation's fossiliferous sandstone.

Beneath the younger volcanic materials lie Cretaceous granitic rocks that have been covered by andesite from the Santa Lucía Range. This layering reveals a deep geological history spanning millions of years.