Black Island, known to many sailors as Bali Hai, is a small, steep island lying between Hayman and Hook islands. 100 Magic Miles describes its West Reef as small scattered coral heads on a silty sand bottom at 3–12 m, with small colourful fish and 2–10 m visibility. It offers an easy 'shore dive' from the north-western corner, where a small beach allows boat-based divers to land and enter without a boat drop. The reef is not dramatic, but the coral heads host a good range of small reef fish, and the silty sand around them can reward macro divers with gobies, shrimps and nudibranchs.

Snorkelling is possible, though the guide notes it becomes deep at high tide. The main hazard is current. Strong offshore currents run past the island, particularly at the northern end, where the tidal stream between Hayman and Hook accelerates.

Divers should stay on the western reef, dive near slack water and not venture north. Black Island is visited mainly by sailing charters and bareboats working the Hayman–Hook area, and occasionally by dive boats looking for an alternative site. Its condition after Cyclone Debbie, which damaged the nearby northern Hook and Hayman reefs heavily, has not been specifically documented.

For those already anchored nearby, it is a reasonable easy dive; it is not a destination in its own right. Skippers should keep a lookout for the tidal race off the northern end when approaching, anchor only on sand in permitted areas and leave someone aboard, as the current can make it difficult for divers to return to an unattended boat.

Boat only. Northern Hook Island is about 22–28 nautical miles from Airlie Beach – roughly 45–75 minutes by fast day boat from Coral Sea Marina or Port of Airlie, or about 1 hour from Hamilton Island marina. Day tours that stop here include Ocean Rafting, Red Cat Adventures (Thundercat), Whitsunday Dive Adventures and Explore Group (from Airlie and Hamilton Island); overnight sailing and bareboat charters also visit.

Private and bareboat skippers must use the public moorings (time-limited, first come first served) and observe no-anchoring areas marked by reef protection markers; bareboat operators restrict where hirers may go. Parking at Airlie is available near Coral Sea Marina and the Port of Airlie. Land on the north-western corner of Black Island for the easy shore-style entry (no facilities).

The northern Hook Island bays face north and are sheltered from the dominant south-east trades (15–25 knots April–September), but they are open to northerly winds and swell (common October–March) and to very strong south-easterlies that wrap around the headlands. Tidal currents through the islands are strong on spring tides (tidal range up to about 4 m) and can make points and bay entrances difficult – plan dives at slack water and neap tides where possible. Visibility is usually 5–15 m, dropping after strong winds, big tides and wet-season rain.

Manta rays visit May–September. Marine stinger season (box jellyfish and Irukandji) runs roughly November to May – wear a full-length stinger suit or wetsuit with hood and gloves, carry vinegar. Cyclone season November–April; tropical lows and cyclones can close sites and damage coral (TC Yasi 2011, TC Debbie 2017).

Severe Tropical Cyclone Debbie (March 2017) badly damaged the fringing reefs of northern Hook and Hayman islands; recovery is ongoing. 100 Magic Miles: strong offshore currents, particularly at the northern end.

Enter from the north-western corner, explore the scattered coral heads on the western reef at 3–10 m, staying away from the northern end where current runs offshore. Snorkel is best at lower tide when the reef is not too deep.

Sailing charters, bareboats and occasional dive-boat visits. Nearest dive centres for gear hire, fills and local advice: Whitsunday Dive Adventures, Explore Group, Ocean Rafting, Red Cat Adventures, Cruise Whitsundays.