The Lanphere Dunes are a National Natural Landmark north of Arcata, at the tip of the peninsula between Humboldt Bay and the Pacific. They protect one of the most intact coastal dune systems remaining in California — a sequence of foredunes, deflation plains, and back-dune forest that has been largely undisturbed for decades thanks to careful management. The US Fish and Wildlife Service manages them as part of the Humboldt Bay National Wildlife Refuge.
Public access is limited to guided tours, typically offered by the Humboldt Bay National Wildlife Refuge on select Saturdays. The tours cover about two miles through the dunes and are free; pre-registration is required through the refuge website. The adjacent Ma-le'l Dunes unit to the south is open for unguided hiking and gives a good sense of the landscape without the restrictions.