Policemans Helmet lies between Duncombe Bay and Anson Point on Norfolk's north-west coast and is named for a distinct rock formation shaped like a British policeman's helmet. Oceanatik calls it an excellent wall dive, with numerous overhangs, a maximum depth of 18 m and rich corals and marine life, and rates it suitable for beginners.

The wall is the main feature, dropping from the base of the rock with overhangs along its length. Overhangs on Norfolk's volcanic walls are typically lined with sponges, soft corals and fans and shelter crayfish, morays, soldierfish and cardinalfish, while the open face attracts wrasse, drummer and sweep. Norfolk's reef fauna generally includes groper, morwong, rock cod and emperors, with kingfish and trevally passing along the wall.

The moderate depth and straightforward profile make it a good introduction to Norfolk's north-coast diving, and it pairs well with the arches nearby. The north-west coast is in the lee of the prevailing south-east trades and is often calm when the south coast is rough, but it is exposed to northerly and north-westerly swell, which makes the overhangs surgy.

The site is dived by boat, usually from Cascade Pier, with a run along the north coast of roughly 20 minutes. Oceanatik lists no species specifically, so the fauna described here is general. Coordinates are approximate. It suits Open Water divers and anyone who likes a relaxed wall dive with plenty of places to look. Take a torch to see colour under the overhangs, and combine it with Cooks Arch or Duncombe Bay for a two-dive trip along the north coast.

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.

North-coast sites are normally reached from Cascade Pier (end of Cascade Road, about 10 minutes' drive from Burnt Pine): the boat runs north-west along the cliffs to the Duncombe Bay area below the Captain Cook Monument, roughly 15–25 minutes. The coast here is within or beside Norfolk Island National Park.

Norfolk's north coast, from Duncombe Bay west to Anson Bay, is in the lee of the prevailing south-east trade winds, so it is the most reliable part of the island for much of the year. It is exposed to northerly and north-westerly winds and swell, more common in summer, which break on the cliffs and pinnacles and cause strong surge. Anything over about 1.5 m of northerly swell closes the boat sites; the beaches need a flat day.

Visibility is typically 15–45 m and often best in winter. There is no stinger season.

Descend beside the rock and follow the wall with it on one shoulder, looking under the overhangs for crayfish and morays. Turn at half air and return a little shallower to the boat.

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).