The Himma is the small, deep and slightly notorious member of the Long Reef wreck group. She began life in 1942 as the Empire Pat, a 274-ton steam tug built by Cochrane and Sons at Selby for the British Ministry of War Transport, and served the Royal Navy in the Persian Gulf. After the war she was renamed Himma and from 1951 to 1972 worked Sydney Harbour as a berthing tug before being sold to Port Moresby interests.

Returned to Sydney, she was scuttled in 1980 by NSW Fisheries as an artificial reef intended to attract fish for anglers; the experiment was judged a failure, but the hull remains for divers. She sits upright on sand at 50 m, the deepest of the group, with the deck at around 46 m and the boiler room floor at 52 m where a large hole in the hull lets you look in. The engine room is empty, the machinery having been removed, but the boiler remains, and between the two a coal bunker compartment survives.

The bridge collapsed around 1999 and the whole superstructure has now flattened, so the wreck presents as a compact tug hull with a surprisingly intact propeller and rudder. It is a fifteen-minute wreck: there is not enough of it to justify a long bottom time at this depth, and most people combine it with a Dee Why or Coolooli dive on another day rather than the same one. Fish life is sparse, kingfish and sergeant bakers being the usual company, and the attraction is really the clear water this far offshore, which often gives 15–20 m visibility over the pale sand.

The Himma carries a sober history: in 1991 two divers died after becoming trapped in a silted lower compartment, which is why local practice is to look but not enter. It suits experienced decompression divers logging the full Long Reef group. Note that one charter website lists the Himma at recreational depth, which is incorrect; every primary source places it at 50 m.

Boat only. Charters and private boats usually launch from the Roseville Bridge ramp on Middle Harbour or Rose Bay/Manly in Sydney Harbour and run north up the coast past North Head, Manly and Dee Why (roughly 45–60 minutes at cruising speed), or from the Akuna Bay/Pittwater ramps and run south past Barrenjoey (similar time). There is no all-weather ramp on the Northern Beaches ocean coast itself.

The wrecks lie on a flat sand plain and cannot be seen from the surface; you need accurate GPS and a sounder, and must drop the anchor or shot line directly onto structure because it will not hold in the sand. A drifting decompression station with spare gas is the normal arrangement.

The Long Reef wreck ground is 4–5 km offshore in open water with no lee. Any southerly or north-easterly swell above about 1.5 m makes anchoring on the wreck and the long decompression hang unpleasant or unsafe; charters generally want under 1 m swell and under 15 knots. Surface current from the East Australian Current can run north–south across the site even when the bottom is still, so a drifting deco station or a strong anchor line is essential.

Visibility is best from late autumn through winter (15–25 m) when the water is clear and cool; summer brings warmer water but more plankton and thermoclines. Avoid the days after heavy rain when the Narrabeen and Hawkesbury outflows dirty the inshore water. Mornings before the sea breeze are calmest.

Short deep dive: descend to the stern deck at about 46 m, look into the empty engine room and the boiler room through the large hull breach (52 m on the sand inside), circle the intact propeller and bow, and return to the shot within 15–18 minutes. No penetration of the lower compartments.

Decompression dive. Typical plans use trimix (e.g. 21/35) or air/EANx with 50% and/or 100% O2 deco gases; 20–25 minutes bottom time gives 30–50 minutes of decompression. Twin cylinders or CCR with bailout, reel/line for any penetration, DSMB and surface support boat mandatory.

Silt inside compartments; several fatalities have occurred on this wreck group, so treat penetrations as overhead dives. Suited to trimix; bottom time realistically 15–18 minutes.

No scheduled recreational charters. Sydney Dive Charters (Rose Bay/Manly) runs technical charters to the Long Reef wreck area on demand for T1/Tec45+ certified divers; otherwise private boats and technical dive clubs launching from Roseville, Akuna Bay or Rose Bay ramps. Expect a handful of visits per year.