Mutton Bird Island — known by its Gumbaynggirr name Giidany Miirlarl — is the small headland at the end of Coffs Harbour's northern breakwall, and the shore dive around its base is one of the most convenient and popular in the whole Coffs region, requiring no boat and offering something worthwhile in almost any conditions thanks to its two very different faces. The sheltered inner side, inside the harbour breakwall, is a gentle, current-free dive in 3 to 10 m that can be entered in almost any weather, while the more exposed outer, ocean-facing side offers slightly deeper ledges to about 15 m for divers waiting for a calm day. Marine life on the inner side leans toward the muck and macro end of the spectrum typical of a sheltered harbour habitat: nudibranchs, moray eels and juvenile tropical fish recruit into the calmer water, and cuttlefish are a regular sighting through the cooler months.

Around the island's base more generally, turtles are common, blue groper patrol the rocky sections, and wobbegong sharks tuck into any available overhang, giving the site a genuinely good chance of the marquee species divers travel to the Solitary Islands for, at a fraction of the cost and effort of a boat trip. Because it sits inside a working harbour, boat traffic is a real and constant consideration here, and divers should stay close to the rocks and well clear of the marked channel, ideally with a dive flag or float when working the more open sections. The site is also a popular local night dive, when the muck and macro life on the sheltered side becomes considerably more active, and it doubles as a training venue for local instructors thanks to its easy access and gentle depth range.

For anyone based in Coffs Harbour without a boat, or simply looking for an easy dive between more demanding trips to the islands, Mutton Bird Island is hard to beat for convenience.

From central Coffs Harbour, walk or drive to the Mutton Bird Island car park at the end of the breakwall (Marina Drive), from which a short walking track leads over the island — divers instead follow the breakwall itself down to the water. Gear up at the car park and carry equipment a short distance to the harbour-side rocks for the easiest entry, or continue around to the ocean side on a calm day for a more exposed dive. No boat is needed for the inner-harbour side; the outer side can also be reached by a short boat trip.

Conditions at Coffs Harbour's shore sites depend mostly on swell direction and the state of the local river/creek systems; sheltered harbour sites like Mutton Bird Island's inner face are usable more often than the exposed outer coast. Visibility drops for several days after the Coffs Creek, Bellinger or Nambucca systems flood following heavy rain. Winter (May-Oct) gives cooler but generally clearer water; summer (Nov-Apr) is warmer with more tropical vagrants.

The inner (harbour) side of Mutton Bird Island is sheltered from ocean swell and can be dived in most weather; the outer, ocean-facing side is exposed and only sensible in small swell.

Enter from the breakwall on the sheltered inner side and work along the base of the rocks at 3-10 m looking for turtles and macro life, or, on a calm day, continue around to the outer side for slightly deeper ledges to 15 m, keeping clear of the boat channel throughout.

No boat required for the harbour side; Jetty Dive Centre runs guided shore and night dives here for students and photography groups, and it is popular with local snorkellers and freedivers.