For my grandparents, and the many, many other refugees and migrants like them, Princes Pier was the first step they ever took on Australian soil. Back in the day this was a bustling port, both for freight and passenger traffic. The long abandoned rails speak to the sheer volume of people that once moved along the now quiet, suburban pier. Before air travel, the combination of Princes, Station, and Town Pier formed the link between Melbourne and the world.
That's not to say Port Melbourne was a particularly... proud gateway. Indeed, the working class, largely poor and industrial suburb was much maligned. A contemporary planning minister complained "it was hard to imagine anything more depressing than Port Melbourne for a first sight of the city."
That is long in the past, however. A good portion of the pier burnt down in the early 2000s, and the government refurbished the remainder to the state you see it in today.
Now, the cache. While ground zero is wheelchair accessible, the cache itself probably isn't, unless you are absurdly flexible. You might need something to poke it with to get it out, but make sure you put it back exactly as it was, including the parts that aren't technically part of the cache.