The Three Sisters is one of several deep reef systems scattered south of Norah Head, sitting in a 22-30 m range that puts it firmly in advanced-diver territory alongside its neighbours the Inner and Outer Bommies. As the name suggests, the site is built around three related rock formations or reef sections, close enough together to be dived as one site but distinct enough to give the dive some structural variety as divers move between them. Detailed published accounts of the site are sparse compared with the area's more written-up wrecks and bommies, reflecting its status as a lesser-known reef mostly known to local club divers rather than a headline charter destination.What is documented points to a typical Central Coast deep-reef profile: solid rock structure supporting sponge, gorgonian and ascidian growth, with resident reef fish using the ledges and gutters between the three formations, and the possibility of larger pelagic visitors given the depth and the general pattern of sightings at similar sites nearby.

Because it sits in the same general offshore zone as the Norah Head bommies and the deeper Central Coast wrecks, The Three Sisters is best treated as an option for club or private-boat divers looking to explore beyond the well-trodden charter sites, ideally with someone who has dived it before to help locate the three formations efficiently rather than searching blind at depth. Divers who do make the trip generally report it as a worthwhile, uncrowded alternative to the well-known bommies immediately to the north, with the added satisfaction of exploring a site most visiting divers never get shown.

Reached by boat from Norah Head or Terrigal Haven, a short run south of the lighthouse; dived by Terrigal Underwater Group and Norah Head Divers Depot.

These offshore sites need a settled weather window with under about 1.5 m swell and light winds, launched from either the rough Norah Head beach ramp or from Terrigal Haven depending on which operator is running. Visibility is generally best in autumn and early winter once the summer's plankton blooms have cleared and before the coldest, greenest winter water sets in, though the East Australian Current can bring clear, warm water south at almost any time of year. A recent blow or heavy rain (Hunter and Tuggerah Lakes runoff) reduces visibility for several days.

Descend to the reef top around 22 m and work through the three main structures that give the site its name, checking ledges and gutters between them for reef fish and invertebrates, before ascending for a safety stop.

Terrigal Underwater Group (TUG) club boat and members' private boats dive these sites regularly; no standing recreational charter runs to the deeper Norah Head wrecks, which are mostly visited by technical-minded club divers on calm-weather trips.