Port Stephens, an open youthful tide-dominated drowned-valley estuary, is a large natural harbour of approximately 134 square kilometres (52 sq mi) located in the Hunter and Mid North Coast regions of New South Wales, Australia.

A harbor, or harbour, is a sheltered body of water where ships, boats, and barges can be moored. The term harbor is often used interchangeably with port, which is a man-made facility built for loading and unloading vessels and dropping off and picking up passengers. Harbors usually include one or more ports. Alexandria Port in Egypt is an example of a harbor with two ports.