Frankston Pier is the northern-most of the Mornington Peninsula pier dives and the closest to Melbourne, sitting at the mouth of Kananook Creek in the heart of Frankston's foreshore precinct. The pier runs roughly 220 m to the north-west over a sand and silt bottom that shelves gently from knee depth at the beach to about 6 m at the head. It is not a dramatic dive, but it is an honest one: the pylons carry a thick fur of sponges, ascidians and hydroids, and the debris field that has accumulated beneath a century of fishing and pier life – shopping trolleys, tyres, bottles and lengths of rope – has become habitat in its own right.

Almost everything worth seeing is under or within a few metres of the structure; the open sand either side is largely empty apart from sand flathead, sea biscuits and eleven-armed seastars. Beyond the pier head, forty metres or more out, a set of purpose-built artificial reef modules sits on the sand and attracts schooling fish and the occasional larger snapper, though it is more visited by spearfishers than scuba divers. The animals that make the dive are the small ones: globefish hanging under the decking, big-belly seahorses gripping the pylon growth, decorator crabs, hermit crabs, spider crabs in late autumn and winter, and smooth stingrays and eagle rays cruising the sand at dusk.

Night dives are productive, with squid, octopus and cuttlefish emerging from the rubble. Frankston Pier is used by the two local dive shops as a confined-water and first-open-water site because it is shallow, sheltered from the prevailing south-westerlies by the coast's orientation only partially, and has facilities right on the beach. It suits newly certified divers, photographers hunting macro subjects close to the city, and anyone who wants a quick, easy dive when the ocean and the southern piers are blown out by southerlies.

Experienced divers will find it shallow and short on topography, but as an evening critter dive it delivers more than its setting suggests.

Frankston Pier is at the western end of Pier Promenade, directly below the Nepean Highway in central Frankston, about 40 km from Melbourne via EastLink or the Nepean Highway. Park in the large foreshore car parks off Nepean Highway or Pier Promenade; it is a flat 100–200 m walk with gear to the pier entrance. Enter from either of the two lower landings on the pier; the first landing is very shallow at low tide, so most divers walk to the second landing nearer the head or enter from the beach on the southern side and snorkel out along the pylons.

Exit by the same landing ladders.

Frankston Pier faces west-north-west into the bay so any westerly or south-westerly wind above about 10–15 knots puts chop and surge along the pylons and drops visibility to a metre or two. Best on easterly to north-easterly winds and near high tide, when there is a little more water over the shallow inner section. Northerlies are tolerable if light.

Visibility drops after heavy rain because Kananook Creek discharges brown water right beside the pier, so leave it a few days after a downpour. Summer weekends bring heavy boat, jet-ski and fishing traffic; early morning or a weekday evening is quieter.

Enter at the second lower landing, descend to 3–4 m and work out along the pylons on the northern side to the pier head, where the artificial reef modules lie 40 m or more seaward in about 6 m. Turn at the head or the modules, return along the southern pylons at 3 m, and finish with a slow swim back under the pier to the landing; no formal safety stop is needed in this depth.

Aquability and Diveline, both based in Frankston, use the pier for Open Water training and occasional guided night dives. No charter is needed; most visits are by independent divers and clubs.