The Yambacoomba is one of the lesser-known Terrigal wrecks, a wooden steamer that COAST Magazine's Central Coast shipwreck roll records as lost at Skillion Rock in 1917 after losing her steering in bad weather. The Terrigal Underwater Group places her remains near Boat Trailer Reef, about 500 m off Terrigal Haven in around 24 m. Spellings vary in the records - Yambacoomba and Yambacoona both appear - which is typical of the small wooden coastal traders that worked this coast in the early twentieth century.

Like most wooden steamers of the period, the Yambacoomba has not survived as a recognisable hull. What divers find is a low, scattered site: iron fastenings and knees, fragments of machinery, and pieces of timber and metal partly buried in sand beside the reef. The attraction is less the structure than the history, and the challenge of reading a debris field - working out where the engine and boiler might have been, and how the vessel broke up after grounding near the headland.

Marine life treats the wreckage as extra reef. Small reef fish, blennies and gobies occupy the crevices, wobbegongs rest in the sand beside larger pieces, and yellowtail and sweep hang overhead as they do across the adjacent reef. Nudibranchs and sea hares are regularly seen on the encrusting growth.

Because there is no published position and the remains are subtle, this is a site to dive with someone who knows it - Terrigal Underwater Group members are the best source - and it pairs naturally with Boat Trailer Reef on a single tank. It suits divers with an interest in maritime history who are happy with a search dive rather than a swim-through wreck, and it reminds visitors that The Skillion has claimed vessels as well as sheltering them. Like all historic wrecks in NSW, it is protected: look but do not remove anything.

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.

The Yambacoomba remains lie close to Boat Trailer Reef, around 500 m off The Haven and only a few minutes by boat around The Skillion. There is no published mark; divers usually visit with Terrigal Underwater Group members or a guide who knows the site, often combining it with Boat Trailer Reef.

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.

Usually dived from Boat Trailer Reef: descend to the reef, then follow a compass bearing given by the guide to the scattered wreckage on the sand. Search slowly for frames, fastenings and machinery, then return to the reef and anchor or ascend on an SMB.

Protected historic shipwreck (NSW Heritage Act 1977, historic shipwreck provisions): artefacts must not be disturbed or removed.

No regular scheduled trips; visited by Terrigal Underwater Group and occasionally by Pro Dive Central Coast as part of a Boat Trailer Reef dive on request.