Islas Marías, UNESCO Biosphere Reserve archipelago near San Blas, Mexico
Islas Marías is a four-island archipelago in the Pacific Ocean, located 100 kilometers off the coast of Nayarit and 370 kilometers from the Baja California peninsula. The largest island, María Madre, served as a federal penal colony until 2019 and now forms part of a UNESCO Biosphere Reserve.
The Mexican government established a federal prison on María Madre in 1905, housing inmates in remote isolation. The facility remained operational for over a century until President Andrés Manuel López Obrador ordered its closure in 2019.
The former penal colony on María Madre houses murals painted by inmates during their time there, showing scenes from prison life. These works remain visible today, documenting life and labor in the colony across more than a century.
Ferry services depart weekly from San Blas and Mazatlán, allowing limited visits to the archipelago with government authorization. The crossing takes several hours across open ocean, so travelers should prepare for changing conditions.
The Salera Salt Mines on María Madre still show buildings and tools from the time when inmates extracted salt there. Remnants of their murals remain visible within these facilities, showing an unusual link between forced labor and artistic expression.
Location: Nayarit
Elevation above the sea: 616 m
Part of: Islands and Protected Areas of the Gulf of California
GPS coordinates: 21.53333,-106.46667
Latest update: December 13, 2025 15:47
Islas Marías Biosphere Reserve
63.2 km
Isla Isabel National Park
69.5 kmIsla Maria Madre Lighthouse
11 kmPlaya El Borrego
123.2 kmPlaya Puerta Palapares
106.5 kmSan Blas Lighthouse
119.6 kmCerro de la Contaduría
123.2 kmBenito Juárez
122 kmPlaca de Fray Junípero Serra
122.2 kmCuautla
112.1 kmMuelle de San Blas
121.7 kmPlaya del Rey
120.7 kmArco de la Entrada de San Blas
122.7 kmFuerte de San Basilio
123.1 kmPiedra Bola de Ahualulco
122.7 kmEl Borrego
122.5 kmPlaya del Rey
121.1 kmPlaca de "Bells of San Blas"
122.2 kmFray Junípero Serra
121.8 kmJosé María Mercado
122.2 kmMuelle de San Blas Escultura
121.7 kmScenic viewpoint
123 kmScenic viewpoint
16 kmCannon
123.1 kmCannon
123.1 kmCannon
123.1 kmCannon
123 kmCannon
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