The ex-HMAS Tobruk is one of the largest dive wrecks in Australia and the reason many divers now travel to Bundaberg and Hervey Bay. Launched on 1 March 1980, she was the Royal Australian Navy's first purpose-built heavy amphibious lift ship, designed to carry up to 500-plus troops, 18 Leopard tanks, dozens of armoured personnel carriers and helicopters. In 34 years of service she supported peacekeeping and humanitarian operations in Somalia, East Timor, Bougainville, the Solomon Islands, Fiji and beyond, before being decommissioned on 31 July 2015.

The Queensland Government scuttled her on 29 June 2018 in 28.5 m in the Great Sandy Marine Park, midway between the two towns. The plan was for the ship to sit upright, but a pump failure during the sinking let her settle on her starboard side. That accident shaped the dive: her uppermost port side lies only about 11 m below the surface, putting a huge amount of the ship within Open Water range, while the deepest point is at about 28-30 m. The site opened to divers in February 2019.

QPWS describes eight deck levels to explore. The highlight is the tank deck – the vast vehicle hold – which can be swum for roughly 100 m from the open stern door towards the bow, with light filtering in through the openings. Troop and crew quarters and other compartments are accessible to trained wreck divers with torches. Outside, the port propeller and rudder sit at about 17 m, and the superstructure and hull are rapidly being colonised by corals, sponges and anemones.

Marine life arrived quickly. Batfish and schools of baitfish swarm the hull, and divers report grouper, cod, Spanish mackerel, wobbegongs, rays, octopus, lionfish and turtles – one green turtle nicknamed 'Brookie' became a local celebrity – with manta rays passing through and humpback whales heard in winter.

Open Water divers can enjoy the exterior; penetration requires wreck training and a guide.

Entry to the wreck area is prohibited without a permit, so almost everyone dives it with a permitted operator. From Hervey Bay, Hervey Bay Dive Centre departs the Boat Club Marina at Urangan Harbour (Buccaneer Drive, Urangan – free parking at the marina) on high-speed boats for a roughly 1-hour, 25 nm run; departure times are set daily to suit the tide and the trip takes about 5 hours. From Bundaberg, operators leave the Burnett Heads marina/boat harbour (15 km north-east of Bundaberg) for a roughly 1-hour, 22 nm crossing – Lady Musgrave Experience has run the trip on its fast catamaran and Bundaberg Aqua Scuba has also been listed as a permitted operator.

Private vessels must book a mooring and dive permit (two-hour slots) through Queensland Parks and Wildlife Service.

The wreck lies in the lee of K'gari, which blocks most southerly and south-easterly ocean swell and is why operators can run it year-round. The limits are wind and tide: trips are cancelled when south-east trades or north-easterlies exceed about 20 knots and the open-water crossing becomes rough, and departure times are set around slack water because tidal current runs across the site on big tides. QPWS gives visibility as 8-20 m, best in winter and on slack tides; summer plankton blooms and wet-season river runoff reduce it.

Water drops to around 20-21°C in winter (5 mm suit and hood recommended) and reaches the high 20s in summer. Cyclone season (November-April) can bring multi-day closures.

Descend the mooring and diver transit line onto the uppermost (port) side at about 11-12 m. The first dive is usually an exterior orientation: along the port side and over the superstructure, down past the port propeller and rudder at about 17 m, and back along the hull. The second dive, for suitably trained divers with a guide, enters the tank deck through the open stern door for a swim of up to 100 m through the main hold, exiting forward.

Hold 20-25 m for the exterior, turn on a third of your gas and return up the transit line, with a safety stop at 5 m.

Designated area with allocated moorings and a diver transit line. Penetration of the tank deck and interior requires wreck training; carry a primary and backup torch and use a line beyond the light zone. Nitrox extends time on the 20-28 m sections.

Hervey Bay Dive Centre (Urangan Harbour) – two guided dives, about 5 hours, 'on demand year round' subject to tide and weather, minimum 4-6 divers; Tobruk Dive Centre Hervey Bay; from Bundaberg – Lady Musgrave Experience (fast catamaran, ~1 hour) and Bundaberg Aqua Scuba. Private boats need a QPWS mooring and dive permit.