The Looking Glass is Broughton Island's signature dive and one of the most photographed grey nurse shark encounters in NSW: a natural crack or arch cut clean through the rock in the shape of an inverted V, connecting open water to a chamber on the far side that local guides call the fish bowl, where sunlight streaming through creates a dramatic, almost cathedral-like lighting effect that is central to the site's appeal. Grey nurse sharks are described locally as practically guaranteed here, typically holding station either inside the passage or in the fish bowl beyond it, and the etiquette for the dive has been refined over decades of guiding: divers transit the gap in single file, usually keeping to the left, so that exhaled bubbles rise on one side of the passage while the sharks are left undisturbed on the other. Depths at the Looking Glass are shallow enough — an eight-metre top down to an eighteen-metre bottom — that surge can be a real factor in anything but calm conditions, and groups need to coordinate their approach and timing to avoid being pushed against the rock walls of the passage.

Beyond the sharks, numbfish and cuttlefish are commonly seen, and the rare eastern blue devil fish has been recorded in a cave on the neighbouring Looking Glass Wall. The best conditions for the full visual effect are a sunny day with the sun close to overhead, when light penetrates the passage and chamber most dramatically; overcast days still deliver the sharks but lose much of the site's celebrated lighting. Because of the shallow depth and the crowd-pleasing combination of striking topography and reliable megafauna, the Looking Glass is dived on almost every Broughton Island trip and stands as one of the true must-do dives on the entire NSW coast.

Boats depart Nelson Bay marina and run approximately 20 km/45-60 minutes north-east to Broughton Island, weather and vessel dependent. There is no facility or dive shop on the island itself; all diving is via day-trip charter from Nelson Bay, typically with two dives per trip around the island's northern and western sides depending on conditions.

Broughton Island sits fully exposed to ocean swell and is the first site cancelled when an easterly or north-easterly blow picks up; operators want well under 1.5 m swell and moderate wind to make the run worthwhile. The island's north side, where the grey nurse shark critical habitat sites (Looking Glass, Shark Gutters, North Rock) are found, gets some lee from a southerly, while other sides suit other wind directions, so skippers choose the exact site on the day. Visibility is best in autumn and winter, typically 10-25 m, and drops after rain from the mainland catchments.

Surge is common in the shallower features like Looking Glass and needs to be managed as a group.

Descend to the outside of the Looking Glass at around 8-13 m and form a single file, usually along the left side, to transit the inverted-V crack through the rock, keeping bubbles to one side so grey nurse sharks holding on the other side are not disturbed. Emerge into the 'fish bowl' on the far side and hold position to watch the sharks in the dramatic backlit conditions, then circle back around the outside of the formation to the mooring.

Let's Go Adventures (Nelson Bay) and Feet First Dive (Nelson Bay) both run daily boat trips to Broughton Island, weather permitting.