Guadalupe-Nipomo Dunes is the largest remaining dune system south of San Francisco and the second largest in the U.S. state of California. It encompasses an 18-mile stretch of coastline on the Central Coast of California and extends from southern San Luis Obispo County to northern Santa Barbara County.

The Guadalupe-Nipomo Dunes undulate for 18 miles along the central California shore, stretching from Pismo State Beach to Point Sal. A steady wind sweeps over them, sculpting the sand into towering peaks that stretch 500 feet into the sky. Sapphire blue waves crash on white beaches. Freshwater lakes are teeming with life. Dunes sprout shrubs of bright yellow daisy-like flowers. It's easy to see why Cecil B. DeMille chose this dramatic windswept setting to film "The Ten Commandments.
Approximately 6,000 acres, including Rancho Guadalupe Dunes County Park, Oso Flaco Lake Natural Area, and the Guadalupe-Nipomo Dunes Wildlife Refuge are now protected.

Rare plants including the surf thistle, beach spectacle pod, and crisp dune mint; 200 species of birds including the endangered California least tern and threatened Western snowy plover; California brown pelican, coast garter snake, and many other insects, lizards, fish, and mammals.