Frankston Reef sits under Olivers Hill, the sandstone bluff that marks the end of Frankston's flat beach and the beginning of the Mount Eliza cliff coast. It is an unglamorous, seldom-mentioned shore dive – The Scuba Doctor lists it as a shallow reef of 2–6 m suitable for Open Water divers – but it is one of the few pieces of natural hard bottom on the bay's north-eastern shore between Mordialloc and Mount Eliza, and that alone gives it more life than the surrounding sand. The reef is low-relief sandstone and rubble with ledges undercut by wave action, patches of brown kelp and Sargassum, and seagrass meadows on the sand flats inshore.

Typical residents are the standard Port Phillip cast: southern hulafish and bullseyes under the ledges, magpie perch, zebrafish, old wives, leatherjackets, dusky morwong on the sand, and octopus and decorator crabs among the rubble. Smooth stingrays and fiddler rays work the sand edge, and in late autumn the reef edge is one of the places spider crabs pass on their way along the coast. It is a site for divers who have exhausted the piers and want a quiet, unstructured poke around close to home, or for Frankston clubs running a shore dive when the pier is crowded.

Being close to a busy boat ramp, it is not a place to dive without a flag, and its very modest depth means it is really a long shallow snorkel with tanks. There is no infrastructure specific to divers; you gear up in the ramp car park and walk down. On a calm winter morning with an easterly, however, it offers surprisingly clear water, empty of people, and a reasonable chance of rays and cuttlefish – a fair reward for a five-minute detour off the Nepean Highway.

From central Frankston follow the Nepean Highway south for about 1.5 km to the foot of Olivers Hill, where the Olivers Hill boat ramp and its car park sit on the seaward side of the highway. Park in the boat-ramp car park (busy with trailers on summer weekends) or in the lay-bys along the highway and carry gear down to the small beach beside the ramp – a walk of 50–100 m. Enter from the beach clear of the ramp channel and swim out over the shallow rock shelf; the reef lies close inshore in 2–6 m.

Exit the same way, keeping out of the boat channel.

The reef faces west and takes the full fetch of the bay in westerly and south-westerly winds, which stir the sand and make the rock shelf a surge zone; anything above 10–12 knots from the west quarter is a poor day. Dive it on easterly or north-easterly winds, ideally around high tide when there is more water over the inshore shelf. Visibility is affected by Kananook Creek and Sweetwater Creek run-off after rain.

Boat traffic from the Olivers Hill ramp is heavy in summer, so a flag and float are essential and early mornings are quieter.

Enter from the beach south of the ramp, surface-swim 30–50 m out to clear the shallows, descend to 3 m and follow the reef edge south with the rock on your left, poking into the ledges and gutters. Turn at about half your gas or when the reef fades into sand at 5–6 m, return along the outer edge and finish over the seagrass inshore.

No regular operator. Occasionally used by Frankston-based shops (Aquability, Diveline) and clubs as an alternative to Frankston Pier; otherwise independent divers only.