The Nornalup Inlet is connected to the much more sheltered
Walpole Inlet through "The Channels" (between Rest Point and The Knoll). The Frankland River flows into the Nornalup Inlet from the east, and the Deep River from the north-west. At the inlet's southern end it meets the Great Southern Ocean. A ridge of low sand dunes and a sand bar separate it from the ocean, but the sand bar never closes over and there's always a narrow channel between the Nornalup Inlet and the sea.
The average depth across the entire Nornalup Inlet is 2 metres, and the maximum depth is 5 metres. Near the river mouths and the sand bar the depth is very shallow and you be careful to follow deeper channels through the sand banks if you're driving a boat.
The Nornalup Inlet has remarkably clear water. If you look down through the water when it's not too choppy, you'll see that almost the whole inlet is covered in seagrasses. There are a few sandy areas, such as off
Coalmine Beach and near the sand bar and
Skippy Rock Channel.
The inlets are
home to plentiful birdlife and marinelife. It's a wonderful place for birdwatching and fishing. Pelicans are very common. There seem to always be a few hanging around
Coalmine Beach.