Martini Creek is a coastal stream whose watershed lies entirely within San Mateo County, California, United States on the western exposures of the Montara mountain block, discharging to the Pacific Ocean. It flows about from its source on Montara Mountain to its mouth in Montara State Beach. This stream has a drainage basin composed of open space and agricultural lands. Some of the basin has moderate to steep slopes and much of the basin habitat is northern coastal scrub, and in places almost of a pygmy forest nature.