The Sand Lake estuary is located on the Oregon coast at Sand Lake. The estuary is approximately 897 acres in area and has a watershed of approximately 17 square miles.

The Sand Lake estuary is designated as a Natural estuary under the Oregon Estuary Classification system. The geomorphology of the area is that of a Bar Built estuary.

The Sand Lake 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.

Sand Lake resembles a coastal river bay without a river. It is a quiet haven for wildlife and canoeists. This estuary is an easy place to spot great blue herons, oystercatchers, and many sea birds. The best access to Sand Lake's birdwatching and canoeing is in Whalen Island Country Park, a very beautiful, often overlooked little park. The former island is now connected to the shore of the estuary with a short, paved road.