The Black Trench Walkthrough – Assassin’s Creed Black Flag Resynced

TL;DR

• The Black Trench is in the Castillo de Jagua region at coordinates 184, 425
• It’s the deepest underwater location on the map — reaching the bottom unlocks the Davy Jones’s Locker trophy
• There are 7 standard chests and 1 secret chest to collect
• The secret chest rewards the Espada Ancha, a rare cutlass — the only shipwreck that doesn’t give a ship upgrade plan
• It’s darker here than any other wreck and jellyfish patrol the area instead of sharks
• The trophy trigger can be finicky — swim around the broken Diving Bell at the bottom if it doesn’t pop immediately

The Black Trench walkthrough in Assassin’s Creed Black Flag Resynced covers the most unique dive in the entire game. Unlike every other underwater shipwreck, The Black Trench rewards a rare cutlass instead of a ship upgrade plan, and it’s the only location that unlocks the Davy Jones’s Locker trophy for reaching the deepest point on the map. It’s darker, deeper, and eerier than any other wreck. Here’s every chest location, the full dive route, and how to grab both trophies in one clean run.

The Black Trench Location

The Black Trench is found in the Castillo de Jagua region, in the northwest corner of the Caribbean map, south of Havana. The coordinates are 184, 425. Sail there and look for a mast or shipwreck marker sticking out of the surface. Pull up alongside it and interact with the prompt to deploy your Diving Bell and drop in.

This is an entirely optional dive. The story never sends you here, so you’ll need to seek it out yourself after unlocking the Diving Bell during Diving for Medicines in Sequence 6.

How to Unlock The Black Trench

Like all underwater shipwrecks, The Black Trench only becomes accessible after completing Diving for Medicines — the 22nd main story mission at the start of Sequence 6. That mission hands you the Diving Bell and automatically marks all 7 shipwrecks on your map.

If you haven’t done the story mission yet, check our San Ignacio Wreck walkthrough which covers that mission in full. Once you’re set up, come back here.

The Black Trench Walkthrough – All Chest Locations

The Black Trench is noticeably darker than other wrecks and the layout goes much deeper into the ocean floor than anywhere else. Instead of sharks, you’ll encounter jellyfish drifting through the area. They can’t be fought, but they’re slow and easy to swim around. The wreck is spread across two sunken ships and a deep rocky trench below them.

Step 1 – Enter and Head Southwest

After the Diving Bell drops you in, orient yourself and swim forward and to the right (southwest). You’ll quickly spot a large rock face appearing on your left side. The two main sunken ships are directly ahead. You’ll see jellyfish drifting around them — this means you’re heading the right way.

Step 2 – Loot the Standard Chests (Main Wreck Area)

The 7 standard chests are spread through the two sunken ships and the surrounding wreck debris. Use L2/LT to scan for white dots constantly — this is especially useful here given how dark the environment is. Check your underwater map regularly to track what you’ve already grabbed.

Each chest rewards around 1,000 Reales. Work through the wreck methodically, using the air barrels attached to the sunken ships to refill your breath as needed. There’s one air barrel on the exterior of the main wreck — save it for when you’re about to go deep into the trench below.

Step 3 – Find the Secret Chest (Espada Ancha)

The secret chest is inside one of the sunken shipwreck pieces within the main debris field. It’s not down in the trench — it’s at the wreck level, tucked at the stern of one of the ships. It’s easy to swim right past, so keep your L2/LT scan active. Open it to collect the Espada Ancha Rare Cutlass.

This is the only underwater shipwreck in the entire game where the secret chest does not contain a ship upgrade plan. If you came here expecting one, you won’t find it — but the Espada Ancha is a strong cutlass that hits hard and is worth having for Edward’s melee loadout.

Step 4 – Dive to the Bottom for Davy Jones’s Locker

After clearing the chests, top up your oxygen at the air barrel on the exterior of the shipwreck. Then dive directly down into the rocky trench below. Keep descending, drifting slightly to the right as you go, until you reach the very bottom of the trench.

At the bottom, you’ll find an abandoned sunken Diving Bell resting on the ocean floor. Swim close to it — hug the sea floor if needed — and the Davy Jones’s Locker trophy and achievement will unlock. This is the lowest accessible point on the entire map.

The trophy trigger can be finicky. If it doesn’t pop immediately, swim around the broken Diving Bell and circle the area at sea floor level. Give it a few seconds before assuming something has gone wrong. If it still doesn’t unlock, resurface, return to the Jackdaw, and try the dive again — a fresh dive usually forces the game to re-register your position.

For a more detailed guide on this trophy specifically, see our guide to reaching the lowest point on the map.

The Black Trench All Chests and Rewards

Here’s a full breakdown of every chest at The Black Trench and what you’ll earn.

• Chest 1 – 1,000 Reales
• Chest 2 – 1,000 Reales
• Chest 3 – 1,000 Reales
• Chest 4 – 1,000 Reales
• Chest 5 – 1,000 Reales
• Chest 6 – 1,000 Reales
• Chest 7 – 1,000 Reales
• Secret Chest – Espada Ancha (Rare Cutlass)

That’s around 7,000 Reales from standard chests plus a rare weapon — solid value for one dive, especially since you’re getting two trophies at the same time if you hit the ocean floor. All 7 standard chests also count toward the overall 68 needed for the Seven Deadly Seas trophy. For all resources and farming tips, see our guide on how to farm metal and wood.

What Is the Espada Ancha?

The Espada Ancha is a Rare Cutlass for Edward’s melee combat. It deals strong damage and is a solid choice if you prefer aggressive close-quarters fighting over defensive play. Since this is the only shipwreck that gives a weapon instead of a ship plan, it’s a welcome surprise for players who stumble upon it.

It won’t help you upgrade the Jackdaw, but for pure combat capability, it’s one of the better blades available at this stage of the game. If you want to know what the best ship upgrades are and where to get them, check our final ship upgrade locations and Ultimate Plans guide.

Davy Jones’s Locker Trophy Guide

The Davy Jones’s Locker trophy and achievement unlocks when you reach the lowest point on the map — the broken Diving Bell at the very bottom of The Black Trench. Here’s the quickest route to trigger it cleanly.

• Deploy your Diving Bell at coordinates 184, 425
• Swim forward and right (southwest) — jellyfish confirm you’re on course
• Pass through the main sunken ships using the broken middle sections to get deeper
• Top up oxygen at the air barrel on the wreck exterior before descending
• Dive straight down into the rocky trench below the ships, drifting slightly right
• Find the broken Diving Bell on the ocean floor and swim close to it
• The trophy unlocks when the game registers you at the lowest point — if it doesn’t pop, circle the area

It’s a quick trophy once you’re in the water. The swim from the Diving Bell to the broken bell at the bottom takes only a minute or two. Do it on the same run as looting all the chests so you don’t have to make a separate trip.

Seven Deadly Seas Trophy Progress

The Black Trench contributes 7 standard chests and 1 secret chest to the 68 total needed for the Seven Deadly Seas trophy and achievement. Visiting it also counts as a discovered Location for the Cartographer trophy. You’re getting three trophies worth of progress in one dive here — that’s the most efficient stop of any wreck in the game.

See our complete underwater shipwrecks locations and loot guide to track your progress across all 7 wrecks.

Tips for Diving at The Black Trench

• Use L2/LT constantly — This wreck is darker than all others. The white dot scanning system is essential here. Don’t try to spot chests by eye alone.
• Jellyfish are harmless but slow you down — They drift unpredictably. Swim around them rather than through them to keep your movement clean.
• Save the air barrel for the deep dive — The barrel on the main wreck exterior is best used right before you descend into the rocky trench for the trophy. You’ll need a full breath for the swim down and back up.
• Do the trophy and the loot in one run — Clear all 7 chests and the secret chest first, then descend to the bottom for the trophy. You’re already down there — no point making two separate dives.
• Don’t rush straight to the bottom — Get the Espada Ancha from the secret chest first. It’s at wreck level, not at the bottom. If you beeline to the ocean floor first, you’ll need to come back up.
• Be patient with the trophy trigger — It’s known to be slightly awkward. Swim around the broken Diving Bell at the floor and give it a few seconds. If nothing happens, resurface and try again.

What to Do After The Black Trench

With The Black Trench cleared, you’ve got one of the most rewarding single dives in the game done — three trophies in one trip if you hit everything. The remaining wrecks that still hold ship upgrade plans worth prioritising are the Kabah Ruins at 738, 120 for the Round Shot Strength Ultimate Plan and the Devil’s Eye Cavern at 453, 323 for the Ram Ultimate Plan.

If you’re focused on fully upgrading the Jackdaw, check out our ship upgrade and customisation guide and our Great Inagua upgrades guide to make sure your Harbourmaster is keeping pace with your plans.

For more exploration content, see our guides on how to capture forts, all naval contract locations, and Kenway’s Fleet.

Haven’t grabbed the game yet? It’s available on PlayStation Store, Xbox, Steam, and Epic Games Store.

More AC Black Flag Resynced Guides

• San Ignacio Wreck Walkthrough
• Antocha Wreck Walkthrough
• All Underwater Shipwrecks Locations and Loot
• How to Reach the Lowest Point on the Map
• How to Beat All 6 Legendary Ships
• Legendary Ships Mortar Trick
• Crafting Guide
• All Treasure Map Locations
• Beginner’s Tips
• What to Do After the Main Story

Frequently Asked Questions