The Islas Marías sit off Mexico's Pacific coast, wrapped in a story spanning centuries of isolation, wildlife, and reinvention. For decades, this remote archipelago was closed to the public, and only recently has it opened its shores to travelers curious enough to look past the mainland. What waits out there is unlike anything else in the region, and the way to reach it is a small adventure in itself.
Where The Islands Are Located
The Islas Marías (Las Tres Marías) are a small archipelago in the eastern Pacific Ocean, lying 132 kilometers from San Blas on Mexico's Nayarit coast and approximately 370 kilometers southeast of the tip of the Baja California peninsula.
The islands were named after three women called Mary in the Bible. Isla María Madre is the largest of the islands, followed by Isla María Magdalena (70.44 km²) and, further south, Isla María Cleofas (19.82 km²). A smaller island, San Juanito, lies just off Isla María Madre.
History Of The Islands
The first European to discover the islands was Diego Hurtado de Mendoza, who named them Islas Magdalenas. The islands served as a penal colony, the Islas Marías Federal Prison, from 1905 until 2019, when President Andrés Manuel López Obrador announced that the prison would close and be replaced with a cultural center named after José Revueltas.
The prison colony was mainly engaged in agriculture, farming, and fishing. Far from the harsh reputation of places like Devil's Island, in more recent times the Islas Marías had harbored mostly low-risk prisoners for whom the "prison without walls" was viewed as a step toward reintegration into society. Some prisoners were even allowed to live with their families.
Ecological Importance
In 2010, the Islas Marías were designated as a UNESCO biosphere reserve, a specially protected biodiverse region.
The Tres Marías Islands are home to a diverse array of flora and fauna, including the Tres Marías Raccoon (Procyon insularis) and the endemic Tres Marías Cottontail Rabbit (Sylvilagus graysoni). The landscape includes grasslands, scrub and deciduous and sub-deciduous tropical forest.
Since the prison closed, researchers have found 21 shark species, 10 ray species, three sea turtle species and healthy coral reefs. Whale sharks visit the waters off the Marías, and other species such as sardines, tuna, and red snapper are thriving. The reserve is also an important nesting and feeding site for large colonies of sea birds.
The mean annual temperature is 24.9C/76.8F, with a historical range of 17.5C/63.5F to 32C/89.6F.
Tourism Plans For Biodiversity And Conservation
The former prison complex has been converted into an environmental education center named after the prison's most famous inmate, José Revueltas, called the Muros de Agua-José Revueltas Environmental and Cultural Education Center.
Visitors can tour the former island jail, specifically the area known as Puerto Balleto, and can now stay overnight in hostel-style lodging.
How To Visit The Marias Islands
Tourism officially opened on the main island on December 16, 2022, with supervised access to designated areas. Ferry routes now depart from San Blas in Nayarit, Mazatlán, and, on a limited schedule, Puerto Vallarta. The boat trip takes about four hours from San Blas and five hours from Mazatlán or Puerto Vallarta. The tour boats are required to anchor southeast of Puerto Balleto, and their guests are taken ashore by tenders.
While we don't currently have a tour to Las Islas Marías, we do have the best tours in Puerto Vallarta. To see the full range of tours we offer, please visit our Puerto Vallarta Tours page.
Frequently Asked Questions About The Islas Marías
Are The Islas Marías Safe To Visit Today?
Yes, the Islas Marías are safe to visit. The Mexican Navy fully supervises access, managing the site as an environmental and cultural destination. Visitors move through designated areas with authorized guides at all times.
Since the archipelago is a protected reserve, group sizes are limited, and activities are structured to safeguard both travelers and the ecosystem, making it one of the most controlled visitor experiences in the country.
Can You Swim Or Snorkel At The Islas Marías?
Swimming and snorkeling are permitted in specific designated zones under the supervision of authorized guides. Because the archipelago is a UNESCO biosphere reserve, water activities are carefully regulated to protect marine life and coral formations.
Visitors should expect a low-impact approach rather than open beach access. Guides brief guests on where entry is allowed and what conservation rules apply before any in-water activity begins on the islands.
Do You Need A Special Permit To Visit The Islas Marías?
Individual permits are not required, but access is only granted through official ferry services and organized tours coordinated by the authorities managing the reserve. Independent boats and private landings are not allowed.
Travelers book their passage in advance through approved channels, and identification is checked at boarding. This system keeps visitor numbers within the limits set for the protected area and ensures every trip aligns with conservation guidelines.
