The TSS Hall Caine is a small, deep wreck with a grim history. Built at Coopernook on the Manning River in 1912, she was a roughly 40 m, 214-ton timber twin-screw steamer designed to carry timber between Wauchope and Sydney. On 17 March 1937 she foundered off Cape Three Points at the mouth of Broken Bay.

Her master reported water in the engine room throughout the voyage, and the Court of Marine Inquiry found the vessel fundamentally unseaworthy - the hull was rotten, the hand pump in bad order, and the boilers unable to raise enough steam to run the other pumps. The judge called her a coffin ship that should never have gone to sea. Divers located the wreck in 1976, and in the years that followed it was heavily plundered of gauges, copper and brass.

What remains, as described by Michael McFadyen, is compact - roughly the footprint of the TSS Wandra off Sydney. The large boiler rises highest, to about 38 m, and is covered in sea fans, sponges and ascidians. Behind it lie the twin engines, with copper and brass fittings still visible between them, and the three-bladed propellers were largely buried in sand when he last described them.

Conger eels live in the fireboxes and boiler tubes, and big flathead lie on the sand. Steel girders, a small winch and unidentified fittings are scattered around, along with commercial fishing nets and ropes. The Terrigal Underwater Group lists the wreck at 44 m, and some sources give up to 54 m for the surrounding seabed.

Either way it is a decompression dive for most divers, with McFadyen suggesting about 14-15 minutes as a typical bottom time. It suits trained deep or technical divers who enjoy small, atmospheric wrecks with a strong story.

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.

From The Haven the boat runs south past Avoca and Copacabana to Cape Three Points, the headland at the northern edge of Bouddi National Park - about 15-20 minutes. McFadyen publishes the position as 33°32.467'S 151°25.433'E (WGS84). The wreck is small and difficult to anchor on, so a shot line is usually dropped from the sounder mark.

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. Deep wrecks also need little current: with the East Australian Current running, lines can stream out and a drifting ascent in open water becomes likely, so operators often wait for neaps or a quiet current day.

Descend the shot to the boiler (top at about 38 m) and use it as the reference. Circuit the boiler, twin engines and stern area on the sand at 43-45 m, watching for netting. After 14-15 minutes (McFadyen's typical time) return to the shot and complete decompression stops per plan on the line or a drifting SMB.

Nitrox or trimix bottom gas depending on team standards; EAN50 or similar for decompression; redundant gas mandatory; carry line cutters. Protected historic shipwreck - no artefact removal.

Deep wreck charters are run on demand by Pro Dive Central Coast and Central Coast Divers (Terrigal) for suitably qualified divers, and by Terrigal Underwater Group and technical diving groups from private boats; there is no daily schedule, so book well ahead and expect minimum numbers and qualification checks.