16lb Reef is the companion in name to 12lb Reef, and it too is named for a monster crayfish – a sixteen-pounder, over 7 kg, which the Scuba Doctor listing says was rumoured to live in the reef for years before its existence was confirmed. Unlike its namesake in Lonsdale Bight, 16lb Reef lies at the ocean end of the Lonsdale Wall system beside Foggy Reef, within a kilometre of Point Lonsdale lighthouse, and the listing gives it 12–18 m with 'many overhangs and small drop-offs' and an Open Water rating.

The site is a shallower shelf of the wall complex where the great cliff breaks down into a series of steps, ledges and undercuts before the reef runs out toward Lonsdale Rock and the Point Lonsdale platform. The overhangs carry the full Heads encrustation – zoanthids, jewel anemones, sponges, soft corals – and the listing picks out 'the spectacular southern blue devil' as the fish to look for, sitting in the crevices; crayfish are in every hole, and old wives, boarfish, magpie perch and wrasse work the face. Because it is at the entrance the water is oceanic and clear, and seals from the point are frequent.

The position, so close to the western jaw of the Rip, means the slack is shorter and the swell more felt than in the bight, and although the depth is Open Water the operators treat it as a site for divers who have already done a Heads dive. It is dived on both slacks, often as the shallower option when Foggy Reef and The Cave are being dived from the same boat by deeper divers. The Scuba Doctor listing describes it as suitable for experienced recreational divers exploring wall formations and crevices, and that is a fair summary.

Boat access only. Charter boats leave from Portsea Pier (Dive Victoria Group, Bayplay) and Queenscliff Harbour (Dive Victoria Group, Red Boats); run time is about 15 minutes. Private boats launch at Sorrento Boat Ramp (Point Nepean Road, Sorrento, all-tide concrete ramp with trailer parking) or Queenscliff Boat Harbour ramp (Larkin Parade, Queenscliff), roughly 15 minutes to the site.

The site is at the ocean end of Lonsdale Wall beside Foggy Reef, near the western side of the entrance. Skippers must call Lonsdale VTS (Point Lonsdale) or listen to VHF 12 for shipping movements before dropping divers, and must carry a dive flag; anchoring is not permitted in the shipping channel, so a live boat and a drop-shot or drift float is the normal method.

It is dived only on slack water, either at the end of the flood (SWF) or the end of the ebb (SWE); most operators prefer the flood slack so that any residual current sets into the bay rather than out to sea. Slack water at Port Phillip Heads does not coincide with high or low water: it falls roughly three hours after high or low water at Point Lonsdale, and the usable window is typically 20–40 minutes. Use the Ports Victoria / Port of Melbourne slack-water predictions for The Heads (also republished by charter operators and WillyWeather 'Rip Bank') rather than a standard tide table.

Being outside or right at the entrance, it is exposed to Bass Strait swell: anything over about 1.5 m from the south-west or south, or a strong southerly/westerly wind against the ebb, produces standing waves in The Rip and charters cancel. Northerlies flatten the entrance and give the best days. Visibility is best in late summer and autumn (Feb–May) when the water is clear and the westerlies have eased; winter brings 11–13 °C water and bigger swells but often the clearest days after a run of settled weather.

Heavy rain has little effect this close to the ocean.

Shot onto the reef at 12 m at slack. Work the overhangs and small drop-offs at 14–18 m with the wall on one shoulder, looking into the crevices for blue devils and crayfish, and reverse along the top; Foggy Reef's anchor and cannons are 90 m to the north-east. DSMB and drift for the safety stop.

Dive Victoria Group (Portsea and Queenscliff) – double boat dives to the Heads walls most days of the week, site chosen on the morning by slack-water time and swell; Bayplay Adventure Tours (Portsea) – weekend and holiday charters; Red Boats (Queenscliff) – weekend Heads charters; Melbourne clubs (VSAG, Power House Underwater Club, Scuba Diving Melbourne) run their own boats here regularly.