Big Sur is a sparsely populated region of the Central Coast of California where the Santa Lucia Mountains rise abruptly from the Pacific Ocean. Although it has no specific boundaries, many definitions of the area include the 90 miles (140 km) of coastline from the Carmel River in Monterey County south to the San Carpoforo Creek in San Luis Obispo County, and extend about 20 miles (30 km) inland to the eastern foothills of the Santa Lucias. Other sources limit the eastern border to the coastal flanks of these mountains, only 3 to 12 miles (5 to 19 km) inland. Another practical definition of the region is the segment of California State Route 1 from Carmel south to San Simeon.