The Sierra San Pedro Mártir is one of the Peninsular Ranges, which run from southern California to the southern tip of the Baja California Peninsula. The San Pedro Mártir range has a very similar flora to the Sierra Juárez mountains just to the north, and these forests, which are surrounded at lower elevations by chaparral and desert shrub, are known as the Sierra Juarez and San Pedro Martir pine-oak forests. The flora is distinct from the flora of the rest of Mexico, and shares many species with the Laguna Mountains and San Jacinto Mountains in southwest California. Typical conifer species include White Fir, Sugar Pine and Jeffrey Pine. Snow usually coats the highest peaks of the range during winter.
The Parque Nacional Sierra de San Pedro Mártir was established by presidential decree in 1974, protecting an area of 650 km² (250 square miles). It was the first of two national parks to be established on the Baja California Peninsula. The other is the Parque Nacional Constitución de 1857, in the Sierra Juárez mountains to the north.
The National Astronomical Observatory is located at an elevation of 2,830 m (9,285 ft). The observatory was built in 1975, and has several large telescopes, the largest of which is 2.1 m (approximately 82 inches). The observatory takes advantage of the high elevation, along with typically clear skies, low relative humidity, low atmospheric pollution, low light pollution, and low levels of radio interference.
Captive-born California Condor have been re-introduced to the wild in the Sierra San Pedro Martir, the first time they have been seen in the range since 1937.