Few people realise that just outside the Australian city of Melbourne lie myriad shipwrecks. Two such wrecks are extremely popular dive-sites amongst advanced level divers. The J4 submarine and the ex HMAS Canberra can be found on the monthly schedule of most dive shops.
The J4 sits at roughly 25 metres and is a hollowed out World War 1 submarine that was scuttled of the headlands of Port Phillip Bay in the 1920s. Divers with a wreck certification can easily penetrate the submarine through multiple hatches in the roof and the broken body at the opposite end. Floating along as the current drags you through the inside of the vessel is an rare and extremely exciting experience. How many people can say they have dived inside a submarine?
The ex HMAS Canberra was an Australian warship retired from services in 2005 and scuttled a few years later as a diving attraction. Numerous hatches and holes have been opened in the vessel to allow light to penetrate nearly every room and allowing a quick exit from everywhere on the ship. This is particularly handy as unlike most wrecks a reel for internal navigation is not required. Unfortunately you must still be wreck certified to penetrate. Although the views from outside are still spectacular!