anti-submarine boom net
...that, during World War II, an anti-submarine boom net to defend against torpedoes and submarines spanned the entire length of Sydney Harbour, Australia?
...that, during <a href="./World_War_II" id="mwBQQ" rel="mw:WikiLink" title="World War II">World War II</a>, an <b id="mwBQU"><a class="mw-redirect" href="./Anti-submarine_boom_net" id="mwBQY" rel="mw:WikiLink" title="Anti-submarine boom net">anti-submarine boom net</a></b> <i id="mwBQc">(pictured)</i> to defend against torpedoes and submarines spanned the entire length of <a href="./Port_Jackson" id="mwBQg" rel="mw:WikiLink" title="Port Jackson">Sydney Harbour</a>, <a href="./Australia" id="mwBQk" rel="mw:WikiLink" title="Australia">Australia</a>?