Johnnystone Rock is one of Norfolk's deeper pinnacle dives. Oceanatik (which spells it 'Johhnystone') describes 'this beautiful rocky pinnacle' rising to within 2 m of the surface and dropping to 30 m, with rock formations, walls and reef, multiple caverns and swim-through passages, abundant marine life and an 'excellent display of enveloping coral formations'. The Marine Life Network describes it as a rocky pinnacle to 30 m with abundant fish. Oceanatik rates it advanced.

The structure offers a lot in one dive. The upper pinnacle is washed by swell and current and attracts schooling fish; the caverns and swim-throughs lower down give shelter and frame the blue water; and the walls carry coral, sponges and fans. Norfolk's fish fauna around pinnacles like this includes kingfish, trevally, groper, morwong, rock cod and moray eels, and Galapagos sharks are sometimes seen around the island's offshore rocks.

The depth makes careful planning important. Most of the interest is between 15 and 30 m, so no-decompression times are short, and with no chamber on Norfolk Island divers should dive conservatively and consider nitrox if available. The caverns should be entered only within sight of daylight.

Norfolk Island Diving will choose the launch pier according to the wind. It suits Advanced divers comfortable at 30 m and in swim-throughs. Visibility is typically 15–45 m, and the combination of structure, depth and coral makes it one of the island's more rewarding dives.

Norfolk Island is about 1,450 km east of Brisbane; flights run from Sydney and Brisbane (about 2.5 h; check the current carrier). A hire car is essential. Norfolk has no harbour: Norfolk Island Diving's open boat is lowered by crane from Kingston Pier (south coast) or Cascade Pier (north-east coast), whichever is in the lee of the day's wind, and divers board from the pier steps once it is in the water.

The site's position is not published; Norfolk Island Diving chooses Kingston or Cascade Pier according to the wind, and most sites are 5–20 minutes from the pier.

Norfolk sits in the south-east trade wind belt. South-easterlies (strongest May–September) make the south coast and Kingston launch rough, and dives move to the north coast from Cascade; northerlies (more common in summer) do the reverse. Any swell over about 1.5–2 m on the exposed side stops the crane launch.

Visibility is typically 20–40 m. There is no stinger season; ex-tropical lows occasionally bring big seas in summer–autumn. Where this site sits relative to those exposures is not published – ask the operator.

Descend on the pinnacle and drop to 20–28 m, exploring the caverns and swim-throughs around the base. Watch no-decompression time, then spiral up the pinnacle and complete the safety stop on its upper section.

Nitrox recommended for the 25–30 m sections if available.

Norfolk Island Diving (local instructor James and divemaster Mitch Graham) – small open boat craned in at Kingston or Cascade Pier depending on wind; runs part-time, mostly weekends, so book ahead by email (norfolkislanddiving@gmail.com).