The cache is located within Alexandra Battery, part of the Derwent's Western Shore defences, which is an abandoned structure that you are free to explore. There are other caches which highlight the Hobart Coastal Defences. For more information, the Wikipedia page is a good starting point in addition to some interpretive signs onsite.
The site is great for kids and dogs with the gun emplacements, underground rooms, and even an underground tunnel, to explore. From the park and observation area uphill there are superb views of the Derwent River, up river to the Tasman Bridge and the City, and down river towards South Arm.
This cache is a tribute to the now-archived cache The Russians are Coming II (GCMPN5). It is NOT at the original location but is nearby. The name presumably referred to the Russian warships which apparently sailed freely into Hobart, which spurred the construction and re-design of the coastal defences. The guns were never fired in anger.