We are seemingly in the middle of nowhere as we sail off the Antarctic Peninsula, with giant icebergs bobbing and snowy peaks protruding.
But as we turn the corner, a tiny wooden hut comes into view. We've reached the southernmost post office in the world.
Port Lockroy postal station is located on Goudier Island, which is roughly the size of a football field. There is no running water or internet and food supplies have to be stockpiled.
The place started out as the first permanent British base in Antarctica during WWII, set up so that the UK could assert a territorial claim.
Stamps are a legal form of currency, so the secret base was run partly as a post office to strengthen sovereignty claims over the continent, to underscore how the British had established a bona fide slice of official territory on it.
Port Lockroy, or 'Base A' as it was initially known, closed in 1962 as Britain established larger and more modern bases on the continent.
But following a conservation survey in 1994, Port Lockroy was recognised for its historical importance and restored by the UK Antarctic Heritage Trust to a working post office, gift shop and museum.
More than 3,000 historical artefacts, including unopened tins of 'luncheon beef' and mashed potato were recovered in the process.
Today, each summer season - which runs from November to March in Antarctica - a team of postal workers are employed to work at the place. Applications are currently open for this year.
So, what does it take to land a job at this remote post office where the temperature regularly dips far below zero and the neighbours include more than 2,000 pongy penguins?
The current base leader, Lucy Dorman, reveals during our stop there that it takes someone with a 'resilient and positive attitude' to do the job.
The post office's main visitors are cruise ship passengers, and more than 18,000 stop off to send mail each year.
Lucy - who runs dog sled expeditions in Canada when she's not down south - adds that because of this high footfall, being a 'people person' is another plus.
She tells me the main tasks at Port Lockroy include talking to guests, scraping penguin poop off the pathways and franking the mail by hand.
More than 80,000 letters and postcards are sent from the post office in the four months or so that it is open.
The mail is taken by ship to the Falklands, where it is loaded on to a military plane and flown to the UK. Once landed, the mail re-enters the British postal system.
The five employees share a bunk room, take it in turns to cook and the toilet consists of a bucket with a lid on it.
There is no internet but there is a satellite phone, which can occasionally be used to make calls home.
The staff get one day off every 14 days but Lucy points out that there is 'nowhere to go when you do get a bit of free time'.
She adds: 'One thing the staff certainly look forward to is a weekly shower. The ships are very generous to us and let it us take it in turns to go on board to wash or do laundry.
'They also give us fresh fruit and vegetables from time to time, which is a big plus.'
Food supplies are sent by ship to Port Lockroy before staff arrive for the season, with several boxes of chocolate being a prize lot. Most goods are tinned or dried.
Summing up her work on the island before I hop on an inflatable zodiac back to my ship, Lucy muses: 'Port Lockroy is a really significant spot and I feel very fortunate to share it with others. It's important to keep this slice of British history alive.'
This article has been adapted from its original source.
