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.

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.