You will be looking for a camouflaged little cache near the Sydney Heritage Fleet. The area is always super busy with walkers and activities, so I trust on your stealth to retrieve this one.
Happy Hunting! :)
Sydney Heritage Fleet, also known as the Sydney Maritime Museum, is a private not-for-profit museum located in Darling Harbor. The Fleet restores and operates a large number of historic vessels including the barque James Craig.

The Lady Hopetoun and Port Jackson Marine Steam Museum was the forerunner of the Sydney Heritage Fleet. In 1965 a group of enthusiasts formed the museum to preserve Sydney's 1902 VIP steam yacht Lady Hopetoun. The organisation later became known as the Sydney Maritime Museum Ltd. In 1998 the museum adopted the trading name Sydney Heritage Fleet. The Fleet now comprises 10 historical vessels which is amongst the largest collection of its type in Australia.

The Lady Hopetoun at Circular Quay c.1910