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 2miles 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.
There are numerous species of flora and fauna which are found in this watershed, including the rare plant Hickman's potentilla. Yellow Bush Lupine is also seen here in a low growing form
The creek name became widely publicized when a highway alternative for the Devil's Slide bypass became dubbed the "Martini Creek Alignment". The highway proposal caused considerable study during the 1980s and 1990s of biology, geology, air quality and acoustics conditions within this watershed.