Butterfly Bay is a deep indentation in the northern coast of Hook Island and one of the most popular bareboat anchorages in the Whitsundays, offering shelter from the prevailing south-easterlies. 100 Magic Miles describes a site of coral outcrops with shallow walls at 5–12 m, with many small, colourful fish, and visibility of 2–10 m. The best snorkelling is along the bay's edges or off the beach, particularly the western reef ledge; towards the centre of the bay tidal currents can be a problem. The fringing reef along the bay's rocky sides is the dive.

Coral outcrops, small walls and ledges host damselfish, butterflyfish (fittingly), angelfish, wrasse and parrotfish, and the bay's shelter makes it a convenient late-afternoon or early-morning dive for yachts anchored overnight. Maori wrasse and turtles are regular, and in winter the bay is one of several northern Hook sites where manta rays may appear. Butterfly Bay was listed by the ABC as 'partially destroyed' by Cyclone Debbie in 2017, when much branching coral was snapped.

Large coral structures survived, and recovery has been underway since; operators and sailors again use the bay for snorkelling, but coral cover will not match pre-2017 descriptions everywhere. The bay is in a Marine National Park green zone, with no-anchoring areas marked over coral – yachts must anchor in permitted sand areas or use public moorings. It suits snorkellers and Open Water divers looking for an easy, shallow reef close to an overnight anchorage.

Its value is convenience and shelter rather than drama.

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. Butterfly Bay is a recognised overnight anchorage for bareboats in south-easterly weather.

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 notes tidal currents are problematic towards the centre of the bay; snorkel along the edges.

Dive or snorkel along the western reef ledge and bay edges at 5–12 m among coral outcrops and shallow walls, staying out of the centre where tidal current runs. Return along the same edge.

Ocean Rafting (Northern Exposure/Southern Lights – daily snorkel stops on northern Hook), Red Cat Adventures Thundercat (daily, Mantaray Bay/Stonehaven), Whitsunday Dive Adventures (certified and Discover Scuba day trips, several times a week), Explore Group (dive and snorkel from Airlie Beach and Hamilton Island, daily), plus overnight sailing vessels and bareboats. Butterfly Bay is especially used by bareboats and overnight sailing trips.