The poet David Harris once described the sea as “a harsh mistress”. It’s likely he wasn’t talking about the ocean in the Sunless Sea, because the words ‘tension’, and ‘horror’ and ‘insanity’ are missing from his work.

In the Sunless Sea, the titular ocean is an ink-black abyss that threatens to swallow whole any who dare venture out into it. Its waters are teeming with danger – giant crabs, sharks, tentacled beasts and enemy ships sidle through the dark – but its true horrifying power is the effect it can have on the people who traverse it.

The year is 1887 and Victorian London has fallen on hard times. The Big Smoke suffered a calamity, sinking beneath the surface of England, obliterating the city’s roads, byways and Burroughs. London now exists by an ocean the locals call the Underzee. The city is surrounded by perpetual darkness and not much is known of what exists beyond her harbour. To that end, the local authorities are offering good money to vessel captains who are willing to venture out into the black and report back their findings.

Players begin the game as one of these many brave (or foolhardy) seafarers tasked with mapping the Sunless Sea. As the game begins they’re able to add an extra narrative layer to the proceedings by picking a back story that dictates a quest they may have to complete – finding their father’s bones, for example. However, the Sunless Sea’s real story begins once the player leaves port with their crew.

The story of the Sunless Sea is one of survival – the player’s survival, to be specific. Each time they leave London’s docks they’re taking their life – and the lives of their crew – into their hands. As they sail through the dark, they’ll come across all manner of dangers, which require use of their ship’s weapons to repel. If they destroy an enemy ship or creature, they can loot the remains for food or examine them to unlock the odd bit of knowledge. Sometimes, however, the only way to stay alive is to cut and run.

But it’s not just that the ocean is filled with dangerous creatures and adversaries that could spell the player’s demise. It’s also the fact that they have to keep a careful eye on their ship’s resources if they want to stay alive. Fuel and food are finite while at sea and if either run out, players could find themselves at the mercy of a most unforgiving environment. At that point, they may even have to turn to cannibalism to stay alive.

If they find themselves lost in the Sunless Sea’s vast expanse, the only recourse players have usually is to plough on. As they do they’ll come across islands and territories in the Underzee where they can stop, resupply and (sometimes) repair any damage to their ship.

Finding a port in the Sunless Sea, however, isn’t a guarantee of safety; while some islands and land spaces house eccentric, yet accommodating folk, there’s also every chance when they step off their boat, the player could find themselves on an island filled with giant spiders. The only truly safe port is that of London, where players can regroup and lower both their own and their crew’s terror levels.

In the event that the player ends up in a watery grave in the Sunless Sea – and inevitably, they will – there’s no saving their progress. The game only offers them ability to leave some of the erstwhile possessions for future versions of themselves to find once they set sail again. The Sunless Sea also has the rather sinister ability to rearrange its layout after the player dies, so certain islands and ports will have moved by the time they start the game again.

Perhaps the most intriguing aspect of the Sunless Sea is how its draw isn’t diminished by its unforgiving nature. Even though the player faces death, madness and untold horrors once they venture out from the safety of London, the adventures they have, the characters they meet and the battles they survive build a compelling narrative around their activities. Each time they successfully return home safely, the exhilaration they feel is close to rapturous.

The Sunless Sea may be a harsh mistress, but above all, it’s also a wise teacher for the player. In their efforts to survive, players will be responsible for some great and terrible deeds and the abyss they travel through will teach them a lot about themselves and the depths to which they’re prepared to sink.

To paraphrase one German philosopher, In the Sunless Sea, you will gaze into the abyss and the abyss will gaze also into you.

Platform: PC (Get it on Steam here)
Cost: $18.99