In the haunting world of Sunless Sea, danger lurks beneath every wave. From malformed leviathans to cunning human foes, the Unterzee is populated by some of the deadliest adversaries in roguelike gaming. In this guide, we break down the five most lethal enemies you’ll face, discuss the top three bosses, and highlight several special mentions—beasts who didn’t quite make the cut, but still warrant respect.

The Core List: Top 5 Deadliest Enemies

5. The Boundling While last on the list, the Boundling is a serious threat. It prowls the depths, never surfacing, and attacks with one of the shortest cooldowns in the game. Though it only averages 18 damage per hit, that speed means sustained barrages. For captains sailing with a modest 75-hull vessel, 4-5 hits spell doom. Thankfully, it’s relatively rare and can be completely avoided by staying above the waves.

4. Wreckship These deceptive foes appear as unassuming wrecks—until they come to life. Durable, agile, and equipped with ranged weaponry, Wreckships average 24 damage per shot and can sink smaller vessels in a matter of seconds. They’re notorious for their unpredictable movement and deadly accuracy. If you’re sailing anything smaller than a Phorcyd-class corvette, avoid them at all costs. Wreckships are responsible for more than a few captain deaths in early and midgame runs.

3. Milliner Bats These aren’t your average bats. With high durability and swarm behavior, Milliner Bats are difficult to target and even harder to kill. Though they deal only 18 damage on average, their persistence and presence near Varchas makes them a rare but formidable threat. They test your patience, positioning, and fire discipline.

2. Blue Prophets Despite dealing only 15 average damage, Blue Prophets rank higher due to their numbers, fast cooldowns, and overwhelming presence across the southern sea. Like the bats, they swarm, but their frequency and attack rate make them a bigger threat over time. They’re common enough to turn routine voyages into bloodbaths for the unprepared.

1. Thalatte The top of the list is reserved for the grotesque titan, Thalatte. It rams for a mediocre 16 damage, but its ranged acid spit can hit for up to 32 damage—and it never misses. Combine that with 420 hit points and you’ve got a beast that punishes even well-equipped vessels. Killing Thalatte is not something you attempt unless you’re well into the mid or late game.

---

Bonus Section: Top 3 Deadliest Bosses

1. Alcaeus-Class Corvette A 16-man warship patrolling near Nuncio and Demeaux Island, this corvette becomes a deadly encounter for early-game captains. Enticing early quests bait players into combat with it, but its rapid rotation and lethal guns demand top-tier navigation skills. It becomes less intimidating in the midgame, but early on, it’s a trial by fire.

2. The Irrepressible Moving like a Wreckship but striking harder, this vessel averages 25–30 damage per hit. While manageable in the late game, its speed and unpredictability make it incredibly dangerous in earlier stages. Avoid unless you’re packing serious firepower.

3. Eater of Names With 700 hit points and three mounted weapons, the Eater of Names is as terrifying as its title suggests. Rare and bound to a specific area, it’s usually quest-tied. Its loot is underwhelming, but its raw power and durability make it one of the scariest ships to fight. Only approach if your quest demands it—and you’re well-prepared.

---

Addendum: The Constant Companion

A terrifying spider-like horror, the Constant Companion didn’t make the core lists due to one saving grace: it’s avoidable. It only appears if you’re underwater and your terror is high—around 60+. Once you understand the conditions for its appearance, evading it is trivial. Still, with 750 hit points, a 40-damage ram, and a decent ranged attack, it remains one of the scariest entities in the game. If you’re well-equipped, though, the loot may be worth the risk.

---

Special Mentions: Dangerous but Manageable

1. Lifeberg These floating glaciers can ram for a brutal 30 damage, but they’re slow and predictable. With upgraded engines and aft guns, they’re easy to kite. Just don’t let them get close.

2. Lorn-Flukes Visually menacing and loot-heavy, Lorn-Flukes are floating urchins with 600 HP. They deal 30 damage with their ram and raise your terror with their AoE. Patience, distance, and low terror are key to farming these safely. If successful, you’re rewarded with secrets and the valuable Fluke Core.

3. Mount Nomad The tankiest of all, Mount Nomad boasts a massive 1,000 hit points, an 80-damage ram, and a 40-damage AoE that spikes terror by 10 points. Yet, it’s surprisingly easy to kite if you stay at range. With the Icarus in Black and 1-2 Doomed Monster-Hunters, you can take it down in two hits. Just tread carefully—failure while harvesting its loot may cost you 1-3 crew.

---

Final Thoughts

These monsters and bosses represent the full spectrum of threats in Sunless Sea—from deceptive wrecks to reality-warping horrors. Some are avoidable, others inevitable, but all are dangerous in their own way. With planning, upgrades, and a healthy respect for the sea’s terrors, you can survive—or even profit—from facing them.

Stay sharp, watch your terror, and keep a finger on the surface button. The Unterzee never sleeps.

This has been Retroburn. Like, comment, share, and subscribe if you found this helpful. Stay cool. Stay frosty.