Fossil Beach is best known above the waterline: in 1854 the marine fossils exposed in its limestone cliffs – shells, sharks' teeth and the remains of sea life from 10 to 15 million years ago – made it one of Victoria's first celebrated geological sites, and a heritage walking track now brings visitors down the bluff. Divers get the same steep path and a narrow rocky shore that The Scuba Doctor lists as a 1–8 m shore dive. Below the tide line the rock continues as a low reef of slabs and boulders fallen from the cliff, broken by sandy gutters and thickly covered in brown algae, with seagrass on the flats further out.

It is quiet, shallow diving of the exploratory kind: turning over the view under each ledge for decorator crabs, hermit crabs, octopus and abalone, watching magpie perch, old wives, zebrafish and leatherjackets patrol the weed, and scanning the sand for fiddler rays, stingarees and sand flathead. In late autumn spider crabs pass along this shore on their way to the southern piers, and in winter giant cuttlefish come into the shallows. The cliff itself is the site's other attraction, and a surface swim along its base at high tide, looking at the layered sandstone, is worth a few minutes.

Fossil Beach is the most accessible and best known of the three little beaches on this cliffed stretch (Coral Cove and Fosters Beach lie to the north), and it is the natural entry for anyone wanting to explore the whole kilometre of cliff-foot reef. It suits divers who like unstructured shore dives and photographers after macro life in shallow, well-lit water. It has no facilities, limited parking and a demanding walk back, and it is not a place for large groups or for anyone who needs more than 8 m of depth.

From Mornington Main Street take the Esplanade north for about 2 km and park in the small gravel car park opposite 631 Esplanade, signposted for the Fossil Beach walking track. The track descends the bluff steeply for about 100 m; take the southern branch to Fossil Beach. Expect a slow climb back with gear.

Enter across the rock and shingle at the northern end of the beach at high tide, when there is comfortable water over the inshore shelf, and swim out to the reef in 3–8 m. Exit the same way. Balcombe Creek and the Mount Martha shore lie further south.

West-facing and open to the bay, Fossil Beach is unpleasant in any westerly or south-westerly wind above about 10 knots, when a shore break runs on the rock and visibility collapses. Choose easterly or north-easterly winds and dive within two hours of high tide so the rock shelf is well covered for entry and exit. There is no current.

Sediment from the soft cliffs and from Balcombe Creek to the south clouds the shallows after rain. Summer afternoons bring a westerly sea breeze almost daily, so mornings are the reliable window.

Enter at the north end of the beach, descend in 2–3 m and swim out perpendicular to shore to the 6–8 m contour, then turn north along the reef edge toward Fosters Beach with the cliffs on your right. Turn at half gas, come back inshore along the 3–4 m ledges looking under slabs, and surface in front of the beach.

No regular operator – independent shore divers, snorkellers and geology walkers; occasionally used by Peninsula clubs for a shallow shore dive.