Sweep City is exactly what the name suggests: a reef where silver sweep gather in numbers. The Terrigal Underwater Group lists it at 24 m and describes it simply as a good reef with plenty of fish life, and it sits among the offshore reefs north of Terrigal that make up the local operators' rotation alongside Bonito Reef, The Pinnacle and Forresters Reef. Silver sweep (Scorpis lineolata) are a characteristic fish of NSW temperate reefs - silvery, deep-bodied planktivores that hang above the reef in loose schools, often mixed with yellowtail scad, mado and one-spot pullers.

On a good day at Sweep City they fill the water over the reef, turning and flashing together, and hanging just above them to watch is a large part of the dive. Predators follow: kingfish and bonito sometimes make passes, and wobbegongs wait at the base of the reef. The reef itself is typical of this depth off the Central Coast - sandstone ledges, gutters and boulders with sponges, sea squirts and small gorgonians on the rock, and kelp in shallower patches.

Red morwong, eastern blue gropers and wrasse move along the ledges, and nudibranchs, sea stars and octopus reward a closer look. Published descriptions are short, and the site is not as well known as Foggy Cave or Two Poles, but locals rate it for dependable fish action. It suits Advanced divers and guided Open Water divers comfortable at 20 m-plus, and it is a good choice for photographers wanting wide-angle schooling shots rather than macro.

All boat dives in this area launch from the Terrigal Haven boat ramp at the southern end of Terrigal Beach, tucked behind The Skillion headland. From the Central Coast Highway follow Terrigal Drive into Terrigal, then Kurrawyba Avenue and Terrigal Esplanade to The Haven, where there is a paid car park beside the ramp; Pro Dive Central Coast's shop is a short walk away and gear is loaded on the ramp or the adjacent beach. Private boats need a ramp with good parking early on weekends as the car park fills by mid-morning in summer.

Sweep City is one of the offshore reefs north of The Haven, a 10-15 minute run depending on conditions. There is no published position; it is dived with Terrigal operators or the local club.

Terrigal's offshore reefs are open to the Tasman Sea and are dived only when swell is below roughly 1.5 m; a north-east sea breeze building through the afternoon in summer and strong southerlies after a front are the usual reasons trips are cancelled, so morning departures are the norm. The Haven boat ramp is sheltered by The Skillion but the run out past the headland can be lumpy in a south-easterly. Visibility is best in late summer and autumn when the East Australian Current pushes warm blue water inshore, and worst after heavy rain when Terrigal Lagoon, Wamberal Lagoon and Avoca Lagoon open and stain the inshore water.

Winter water is cooler (around 15-17 °C) but often clear. Deeper offshore reefs also need manageable current - when the East Australian Current runs hard, skippers may skip them for sites closer in.

Descend the line, then circle out from the anchor along the reef edge at 20-24 m. Spend time mid-water above the reef top watching the sweep schools before returning to the anchor.

Pro Dive Central Coast (Terrigal Haven) runs boat dives from The Haven most days, weather permitting; Central Coast Divers also runs Terrigal charters; the Terrigal Underwater Group dives the site from club and members' boats. It is usually offered as a second dive or when conditions or demand favour reef sites over the ex-HMAS Adelaide.