Supply Bay is situated on the western bank of the Tamar River, approximately 30 minutes drive North of Launceston.
The Supply River flows into Supply Bay, and is the site of Tasmania's oldest water driven flour mill (1825 -1888).

The ruins of the mill are still standing today, and can be accessed by a walking track from the Supply River Bridge on the Deviot road between Gravelly Beach and Deviot.
On the southern side of the bay nestles the hamlet of Paper Beach, the home of Supply Bay Design.