The islands were used as a penal colony until February 18, 2019, when President Andrés Manuel López Obrador ordered the closure of its operation as Islas Marías Federal Prison.

[2] The first European to encounter the islands was Diego Hurtado de Mendoza, a cousin of Hernán Cortés in 1532, who gave them the name Islas Magdalenas.

[4][5] The islands have an aggregate area of 244.97 km2 (94.58 sq mi) and a population of 1,116 on Isla María Madre as of the census of 2005 along with around 8,000 prisoners.

A smaller island, San Juanito, with an area of 9.1 km2 (3.5 sq mi) lies off the north coast of Isla María Madre.

[1] The islands are listed from north to south in the following table: Research supports the hypothesis that the Islas Marias are fragments of continental crust left over from the separation of the Baja California Peninsula from the mainland of Mexico.

[10] These variations, due to tectonic rifting, uplift and sea level fluctuations, had a major impact on the population dynamics of the islands' biota.

The National Hurricane Center reported at 9 AM MDT "Aircraft finds the core of Willa passing over Las Islas Marias Mexico".

[23] One of its more notable prisoners was the Mexican progressive writer Jose Revueltas who wrote his first book Los Muros de Agua [es] (The Walls of Water) while incarcerated there.

[24] The idea of a penal colony in the Marías Islands was not new, as it had been considered by previous governments, such as those of Benito Juárez and Maximilian of Habsburg.

[25] However, it was under Porfirio Díaz that the proposal came to fruition, as part of his efforts to implement a penal reform that would guarantee social control, the availability of labour and the protection of foreign investment.

Subsequently, in 1905, the Islas Marías were officially declared a penal colony and the penalty of descent was introduced as a form of punishment.

[26] The director of the penal colony, Arturo G. Cubillas, played a decisive role in the adaptation and application of the penalty of descent.

[28] Another group of settlers is made up of religious ministers and acolytes of the Catholic Church, nuns of the Order of Social Service, and invited teachers, technicians and their relatives.

[28] President of Mexico Andrés Manuel López Obrador announced on February 18, 2019, that his administration would close the Islas Marías Federal Prison, replacing it with a new cultural center that will be named for José Revueltas.