Nehalem Bay State Park, State park on Pacific coast in Tillamook County, United States.

Nehalem Bay State Park occupies a sand spit about 4 miles (6 km) long between the Pacific Ocean and Nehalem Bay, covering 362 hectares in Tillamook County. At the entrance road a brown sign reads "Welcome to Nehalem State Park", and further on a log archway carved with "NEHALEM BAY STATE PARK" spans the roadway. The campground has 265 sites with water and electricity plus 18 yurts, and Nehalem Beach lies within the park.

The area was transferred to Oregon in 1938 with plans to become a recreational park. It officially opened as a state park in 1972 after additional land was added.

The park takes its name from Nehalem Bay and the Nehalem River, which flows into the bay at its estuary. The Tillamook County land was handed to the State of Oregon starting in 1938, with further parcels transferred or bought from private owners until 1963. Summer interpretive programs are held in the park amphitheater.

The campground has 265 sites with water and electricity plus 18 yurts, and it also takes tents, horse riders, hikers and bicyclists. The Nehalem Bay State Airport strip lies inside the park for small planes. The spit runs about 4 miles between the Pacific and Nehalem Bay, so expect wind and blowing sand on the beach side.

An active airstrip sits within the park grounds, welcoming small aircraft since 1958. This working runway makes the space one of the few parks where aviation and nature coexist.