The Round Shot Strength Ultimate Plan is in an underwater chest at the Kabah Ruins Diving Bell site in Navassa, around coordinates 738,120, reached by following the jellyfish-marked tunnel from the diving bell and pushing through the current to the chest at the end.
The Round Shot Strength Ultimate Plan is a short underwater pickup, but the route is easy to miss once you leave the bell. Treat it as a landmark run: get to the correct Diving Bell site, follow the jellyfish into the cavern, manage your air, then commit through the final current until the chest is in reach.
Kabah Ruins location and requirement
| Detail | Value |
|---|---|
| Plan name | Round Shot Strength Ultimate Plan |
| Region | Navassa |
| Diving Bell site | Kabah Ruins |
| Approximate coordinates | Around 738,120 |
| Prerequisite | Main-story Diving Bell activity unlocked |
| Chest type | Underwater treasure chest |
| Upgrade unlocked | Final Round Shot Strength upgrade path for the Jackdaw |
Set your course for the Kabah Ruins Diving Bell in Navassa, in the southeast/bottom-right portion of the sea map. The bell is only useful after the main story has opened Diving Bell activities, so complete the first campaign mission that uses the Diving Bell before making this collectible run.
KEY!The chest is part of the underwater route, not a surface wreck pickup, so arriving at the correct marker is only half the job. Once the bell lowers Edward into the site, the plan is at the end of the cavern route below.
How to reach the Round Shot Strength Ultimate Plan chest in Assassin’s Creed IV: Black Flag
Start from the Kabah Ruins Diving Bell and use the jellyfish path to reach the current tunnel that hides the plan chest.
STEP 1/9
Activate the Diving Bell
Start the bell activity at Kabah Ruins after Diving Bell sites are unlocked through the main story.
STEP 2/9
Leave the bell and face the ruins
Swim out from the bell, keeping the temple ruins on your right as your first landmark.
STEP 3/9
Drop toward the jellyfish
Look down to the left for the jellyfish cluster and follow it away from the bell.
STEP 4/9
Enter the secret cavern
Swim into the hidden cavern below the jellyfish and continue as far back as the tunnel allows.
STEP 5/9
Refill air at the bubbles
Rise into the air bubbles when you see them, then return to the same tunnel path.
STEP 6/9
Stop at the dead end
When the tunnel closes off ahead, pause at the dead end instead of turning back.
STEP 7/9
Turn right into the current
Turn right from the dead end and start pushing into the current-heavy passage.
STEP 8/9
Push through each surge
Keep pressing forward as the current knocks you back, using each lull to gain a little distance.
STEP 9/9
Open the chest
Loot the chest at the end of the tunnel to receive the Round Shot Strength Ultimate Plan.
Video help
Storms, oxygen, and the tunnel current
The first blocker can happen before the swim begins. If a storm is active or a ship is obstructing the Diving Bell activity, the game will make you wait until the weather clears or the obstruction moves away.
Inside the cavern, use air bubbles whenever the route offers them. The tunnel is longer than it first looks, and reaching the final current with low oxygen makes the last push much more punishing.
The current near the end works in surges. Keep holding forward through the lighter push, use the wooden beams for momentum, and tuck into the small nook when the hard surge is about to shove Edward back; once it fades, move again and take the next gain.
Pause in the small nook during the strongest current surge, then swim forward as it fades so each attempt gains ground instead of burning air.
Buying the Jackdaw upgrade after the plan
KEY!Looting the chest adds the Round Shot Strength Ultimate Plan to Edward’s inventory and opens the final upgrade tier for the Jackdaw. It does not install the upgrade by itself.
After leaving Kabah Ruins, visit a Harbourmaster, open the ship upgrades, and buy the remaining Round and Heated Shot tiers in order. At Great Inagua, make sure the Harbourmaster stall is fully upgraded if the final plan-based tier is missing.
Frequently Asked Questions
Where is the Round Shot Strength Ultimate Plan in Assassin’s Creed IV: Black Flag?
It is inside the underwater treasure chest reached from the Kabah Ruins Diving Bell site in Navassa. Follow the jellyfish into the hidden cavern, then stay with the tunnel until the chest at the far end.
What coordinates should I use for Kabah Ruins?
Use 738,120 as your marker; nearby readings such as 740,118, 738,117, and 741,126 point to the same Kabah Ruins Diving Bell area.
Why can’t I start the Diving Bell activity?
You need to complete the main-campaign mission where Edward first uses the Diving Bell. If that is done and the prompt still will not work, wait for any blocking storm or ship to pass.
Does looting the plan automatically upgrade the Jackdaw?
No. The plan only makes the final Round Shot Strength tier available; the upgrade still has to be purchased through a Harbourmaster after the earlier requirements are met.
What should I do if the current keeps pushing me back?
Do not reset the route. Hold forward during the weaker flow, use the wooden beams and side opening to recover position, and wait out the strongest surge before making the next push.
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