Black Bank is a boulder reef off Norfolk's north coast. Oceanatik describes it as 'a beautiful boulder reef' with 'many caves, arches and swim-throughs', the formations outlined with corals, sea fans, anemones, sponges and sea stars, and 'an excellent display of marine life in abundance' – 'a very interesting and colourful dive'. The Marine Life Network gives the depth as 21 m and places it on the north coast.

Boulder reefs make for varied diving. Where large boulders pile against each other, the gaps form caves, arches and swim-throughs, and the surfaces provide space for encrusting life. At Black Bank the corals, sea fans and sponges colour the boulders, anemones host anemonefish, and sea stars are common on the rock. The caves are the likely places to find crayfish, morays, soldierfish and cardinalfish, while wrasse, sweep, drummer and butterflyfish move over the reef.

Oceanatik rates it beginner-friendly, and at 21 m it is within Open Water limits, although newer divers should follow the guide through the swim-throughs and avoid them in surge. The north coast is sheltered from the prevailing south-east trades and is dived by boat from Cascade Pier; it closes in northerly swell.

The name 'Black Bank' suggests a dark basalt bank familiar to local fishers, and many of Norfolk's dive sites share names with traditional fishing grounds. The exact position is not published, so coordinates are left blank. It is a good choice for divers who enjoy structure and colour without great depth. Take a torch for the caves.

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 onto the boulder reef and explore it at 14–21 m, taking the swim-throughs and arches that the guide points out and checking the caves for crayfish and morays. Return shallower along the boulders.

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).