J3 was launched at Portsmouth Naval Dockyard on 4 December 1915 and commissioned into the Royal Navy in April 1916, one of the seven fast J-class boats built to work with the Grand Fleet. Six of the class came to the Royal Australian Navy in 1919 and were based at Geelong until budget cuts paid them off at Western Port in July 1922. Where J1, J2, J4 and J5 went to the Ships' Graveyard, J3 was kept closer to home: stripped of her machinery, she was scuttled in January 1926 as a pier and breakwater off Swan Point on Swan Island, then the Army's fortress and mine depot guarding The Rip, where her hull also served as a landing stage and power source for the base.

She lies upright on the seabed in about 6 m with the upper deck and the base of the superstructure protruding above water, bow to the east-north-east, roughly 100 m from the island shore. Unusually, she rests on top of an earlier breakwater hulk, the 961-ton coal hulk S. F.

Hersey, whose remains lie 178 m to the south-west and under her stern. J3 was the only three-screw boat of the class and the distinctive triple shaft arrangement is still visible at the stern; her two bronze propellers were removed years ago and are displayed at the Queenscliffe Maritime Museum. The pressure hull is intact for most of its length, with hatch openings and the casing gradually collapsing, and inside the bay the iron carries a coat of sponges, ascidians and small fish – leatherjackets, wrasse and seahorses in the weed.

The problem is access. Swan Island is a Department of Defence facility and the waters around it, including the J3, are a prohibited area; the Scuba Doctor states plainly that the submarine is out of bounds without special permission, and charters do not visit. It is included here because it is the most complete and most visible of Victoria's J-class boats and every Queenscliff charter passes it on the way out; realistically it is a boat-viewing or museum experience rather than a dive.

The J3 lies 100 m off Swan Point on the eastern side of Swan Island, about 2 km north of Queenscliff Harbour, and is normally out of bounds: the island is a Department of Defence facility and the waters around it are a prohibited area. In the past divers reached it by small boat from Queenscliff ramp (Larkin Parade) in five minutes, anchoring on the lee side; today that requires written permission from Defence, which is rarely granted. Drive Melbourne–Queenscliff via the Geelong Ring Road and Bellarine Highway (about 1 h 40 min).

The submarine can be seen from the water on the way out of Queenscliff and from the Swan Bay side, and the two bronze propellers removed from her are displayed at the Queenscliffe Maritime Museum on Weeroona Parade.

The site is in the tidal channel between Swan Island and the Queenscliff shipping approaches. Tidal streams run up to 2 knots across the long axis of the hull at full flood or ebb, so any dive would have to be at Port Phillip Heads slack water (the Scuba Doctor notes the lee side of the hull is workable on a running tide but the up-stream side is not). Wind chop from the south and west builds quickly across Swan Bay; a calm morning is needed.

Visibility in this part of the bay is 3–8 m and is best on the flood after a dry spell. None of this matters unless Defence permission has been obtained – the prohibited area is enforced.

If permitted: anchor on the lee side at slack water, drop onto the hull in 5–6 m and circle the 84 m boat from the east-north-east-pointing bow to the stern, where the three propeller shafts (two propellers removed) and the coal hulk S. F. Hersey beneath the stern can be seen.

Stay on the sheltered side once the tide turns.

No operator. Dive Victoria Group and Red Boats pass the wreck en route to The Heads and it appears on their site lists, but no charter dives it – access requires Department of Defence permission for the Swan Island prohibited area, and in practice it is viewed from the boat only.