The SS Irresistible was one of the steam tugs that served Newcastle's busy coal port. Grey Nurse Charters records that she was built in London in 1883, worked for J & W Brown, the Newcastle towage company, and was scuttled on 27 August 1931 - one of several old tugs disposed of off Newcastle that year, along with the Commodore and the Osprey. She now lies in about 26 m in Stockton Bight, past North Reef; the nearby reef called The Limestones is described as being near the Irresistible wreck.

The wreck sits upright on sand. Grey Nurse Charters describes a large boiler separated by sand from the engine and propeller shaft, and a forward section - so the hull has partly collapsed and the machinery is the main structure. For a tug, the boiler is big and dominates the site, and the engine and shaft make a clear line toward the stern.

As an isolated structure on sand, the Irresistible attracts wobbegongs and reef fish; yellowtail, bullseyes, leatherjackets and morwong are typical, and encrusting growth covers the metal. Because Newcastle visibility varies with the Hunter outflow, the best days follow dry weather and coincide with high tide. At 26 m the dive suits Advanced divers, and the compact layout means the whole wreck can be seen in one dive.

It is a good introduction to the Newcastle tug wrecks, which progress from the Irresistible to the deeper Commodore (36 m) and Osprey (42 m), and it pairs with The Limestones reef nearby.

Charters and private boats leave from Newcastle Harbour - the Carrington or Stockton boat ramps, or Newcastle Cruising Yacht Club/Marina precinct on Wharf Road - and run out past Nobbys Head through the harbour entrance, a busy commercial shipping channel where port traffic has right of way and Port Authority rules apply. Parking with trailer bays is available at both ramps. After clearing the harbour, the boat heads north-east into Stockton Bight past North Reef - roughly 15-20 minutes.

No public mark is published; the site is dived with Grey Nurse Charters or local boats with the position.

The Newcastle offshore sites are exposed to the full Tasman swell and generally need less than about 1.5 m of swell and light winds; strong southerlies and north-easterlies both make the run from the harbour uncomfortable. Visibility is the main variable: the Hunter River outflow through the harbour entrance stains the water for days after rain, so the best diving follows a dry spell and is usually timed around high tide, when clean ocean water pushes in. The East Australian Current brings warmer, clearer water from late summer into autumn, while winter can be cold (around 15-16 °C) but surprisingly clear.

Descend the shot to the wreck. Start at the forward section, move aft to the large boiler, then cross the sand gap to the engine and propeller shaft. Return along the wreck to the shot for the ascent.

Combine with a look at The Limestones on a second dive.

Historic shipwreck protections apply (scuttled 1931).

Grey Nurse Charters dives the Newcastle wrecks and reefs by arrangement from Newcastle Harbour and Swansea; Dive Newcastle and local clubs dive them from private boats. There is no fixed daily schedule - trips run on demand and conditions.