Bonito Reef is a compact ridge of reef off Crackneck Point, the forested headland in Wyrrabalong National Park between Forresters Beach and Bateau Bay. Muddy Puddle Diver records that it was discovered while fishing and describes it as a finger of reef, a ridge running roughly east-west, with the top at 21 m and the base at 25 m. The Terrigal Underwater Group lists it at 25 m and praises its excellent structure, many nudibranchs and good fish life.

The ridge form makes for easy navigation: one side out, the other side back. Along the flanks the rock is undercut, with ledges and small overhangs where bullseyes, one-spot pullers and cardinalfish shelter. The top is cloaked in sponges, ascidians and encrusting growth, and it is here, and on the vertical sides, that the site's nudibranch reputation is earned - several species can be found on a single dive by divers who slow down and look closely.

Fish life is good for the size of the reef, because an isolated ridge on sand concentrates fish. Yellowtail and silver sweep school above the top, red morwong and blue groper patrol the edges, wobbegongs lie at the base, and in warmer water there is a chance of the pelagics - bonito, kingfish and trevally - that probably gave the reef its name among fishers. At 21-25 m it suits Advanced divers, or Open Water divers with a guide who are comfortable at depth, and it offers enough time at depth for photographers to work.

It is a good choice when the Adelaide is busy or divers want a reef with real relief and a strong macro component.

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.

Bonito Reef is off Crackneck Point, the headland between Forresters Beach and Bateau Bay, about 10-12 minutes north of The Haven. The ridge is narrow, so skippers anchor on it using GPS and sounder.

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 to the ridge top at about 21 m and follow the ridge east or west along one side at the sand line (25 m), then turn and return along the other side. The ridge makes a natural out-and-back route back 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.