The Shark Gutters are the reason most divers first come to Fish Rock: four or five parallel gutters cut into the rock at 45 degrees off the south-eastern corner of the island, their ridge tops around seven metres near the rock and their floors sloping to 24-30 metres a hundred metres or more offshore. Some gutters are open-ended, running out into open sand, others close off against the reef, and black coral trees — bleached white by depth — mark the more current-exposed corners. This is the main grey nurse shark cruising ground at Fish Rock: in winter and spring it is common to see up to a dozen sharks holding station in the gutters, motionless but for gill movement, and exceptional counts of thirty or more have been logged in peak years.

The etiquette here matters — divers are asked to stay out of the gutter itself and watch from the rim or the ridge, which both protects the sharks and gives a better view as they cruise the length of the channel below. Away from the sharks the gutters hold their own reef life: sponge gardens, firefish tucked into small overhangs, long-snouted hawkfish perched on the black corals, and schools of pomfret and silver sweep moving through the current lines. Visibility here is usually very good — 15 to 30 metres and sometimes better — because the gutters sit clear of the turbid inshore water, though a wrap-around current is common and can pick up through the day.

Because the gutters lie directly beside the main southern mooring, this is the standard first stop on almost every Fish Rock trip before divers head into the cave or across to the Aquarium, and for many divers it is the single best chance in NSW to spend a whole dive at close but respectful range from a resident population of critically endangered grey nurse sharks in clear water over an interesting rock structure, rather than a fleeting drift-past encounter.

All Fish Rock sites are boat access only, departing from the boat ramp/marina at South West Rocks (Fish Rock Dive Centre and South West Rocks Dive Centre both operate from the town, 4 New Entrance Road area). The run out to Fish Rock, off Smoky Cape about 2 km offshore, takes roughly 15-25 minutes depending on the vessel and sea state. Boats moor directly on the site — there is a southern mooring near the cave/shark gutters and a northern mooring near The Pinnacle — so there is no surface swim; divers descend the mooring line straight onto the reef.

Double boat dive trips (two dives, roughly 5 hours total) run most days when weather allows; book ahead as Fish Rock is a signature Australian dive and trips fill, especially in the May-November grey nurse season.

Fish Rock sits in open ocean off Smoky Cape with no shelter, so trips are cancelled on any strong onshore swell or wind over about 20 knots; operators want under 1.5-2 m swell to run safely. The site is affected by a north-setting current for roughly 80% of the time, and it can run strong enough to make the cave and Pinnacle undiveable — the best conditions are the day after the current has dropped out or during a brief slack. Visibility is usually 15-30 m and can be exceptional (30-40 m) inside the cave itself; it drops after east coast lows and heavy rain runoff from the Macleay River.

Grey nurse sharks are present year-round but peak May-September, with leopard (zebra) sharks more likely February-April. Dived year-round; winter mornings before the sea breeze are usually calmest.

Descend the mooring onto the ridge top at about 7 m and drop into the nearest gutter, following its sandy bottom out to the south-east where it deepens to 24-30 m. Rather than swimming in the gutter itself, sit along its rim to watch grey nurse sharks cruise beneath, then cross north into the next gutter along and work back toward the island, finishing on the shallower ridges for the safety stop.

Fish Rock Dive Centre (South West Rocks) — double boat dives most days, year-round; South West Rocks Dive Centre — daily boat trips to Fish Rock.