If you are ever in Sydney and you don’t mind a ferry ride over the harbour, we recommend dropping in to see this memorial.

Take the ferry to the Taronga zoo dock, then follow the path off to your right. It will take you around the headland right into the memorial at Bradleys Head.

You can see here on our miniature the part of the ship that was used for the memorial. Here is some details from wiki about the ship and her service:
HMAS Sydney was a Chatham-class light cruiser of the Royal Australian Navy (RAN). Laid down in 1911 and launched in 1912, the cruiser was commissioned into the RAN in 1913.

During the early stages of World War I, Sydney was involved in supporting the Australian Naval and Military Expeditionary Force, and escorting the first ANZAC convoy. On 9 November 1914, she defeated the German cruiser SMS Emden at the Battle of Cocos.

There is another part of this story that exists in a more accessible part of Sydney. A gun from the SMS Emden.

It was a bit of a hike from the Blue Mountains for Aaron and Ben but well worth the time.