The Tillamook Bay estuary is located on the Oregon coast at Tillamook and Garibaldi. The estuary is approximately 9216 acres in area and has a watershed of approximately 540 square miles.

The Tillamook Bay estuary is designated as a Shallow Draft Development estuary under the Oregon Estuary Classification system. The geomorphology of the area is that of a Drowned River Mouth estuary.

The Tillamook Bay estuary is located in Tillamook County. The principle industries of Tillamook County are agriculture, lumber, fishing, and recreation. Dairy farms dominate the county's fertile valleys providing milk for the well-known Tillamook cheese. Logging and lumbering are becoming a significant economic force again due to the reforestation of most of the 'Tillamook Burn' area. With seventy-five miles of coastline, four bays, and nine rivers, recreational and tourist facilities are numerous. The 1997 population of Tillamook County of 23,800 represented an increase of 10.3% since 1990.

The scenic, sandy peninsula sheltering Tillamook Bay not only has some of the coast's best birdwatching, it's the site of one of Oregon's strangest ghost towns. An old road, closed to unauthorized motor vehicles, allows bicyclists to tour past the vanished town along the bayfront 4.4 miles to the jetty at the scenic bay's mouth.