The reunion session ended on the deck at evening โ the crew together, drinks found, the harbour quiet. This session ends that quiet. The World Government responded to the Gravemark battle. They responded to the Den Den Mushi report that Rokuji of the Phoenix Pirates โ bounty เธฟ1,486,000,000, confirmed dead at Marineford โ is alive and in Sabaody harbour.
The crew has to move. The Miku has to move. And the only safe route off this island is down.
Tone shift from the reunion. The reunion was warm and loose. This session is urgent. Not panicked โ these are post-timeskip pirates who have each been through a crucible โ but genuinely pressured. The escape should feel like the crew operating together at full capacity for the first time since the timeskip. Everything they learned, deployed together, under time pressure.
The Three Acts
Session Structure
Act One โ The Alert: Marine horns in the upper harbour. The crew has a window. How long depends on how smart they are about it.
Act Two โ The Prep and the Chase: Ten minutes to dive. The Marines know how long it takes to get a ship underwater. They're counting.
Act Three โ The Deep: The dive itself. The silence. What the ocean looks like when you're inside it. Fishman Island appearing below them like a city made of light.
Opening Beat
The Horns
Begin this session immediately where the reunion ended โ no gap, no time skip. The crew is on the deck. The drinks were just found. Smokey is settling in. And then:
The first horn is distant. Upper harbour โ the Sabaody Marine Command post on Grove 66.
The second is closer. A patrol ship changing course.
The third is the bubble lift system locking down โ all civilian transport halting simultaneously. The Archipelago does this when it identifies a Priority Target in the harbour. You've seen it happen before. You were on the other side of it.
Somewhere in the upper groves, a Den Den Mushi is transmitting a description of your ship.
Kaillou. He already knows. He was watching the upper harbour from the moment the reunion settled. He has the routes in his head. He says nothing yet โ he's waiting to see if anyone else catches it first. When they don't, he says one word: "Now."
The Window
How Much Time They Have
The Marine response time from Priority Alert to blockade is approximately 25 minutes in Sabaody harbour. This is their window. 10 minutes of that goes to the dive prep. 15 minutes to get clear of the harbour mouth before the blockade closes.
This is tight. It is deliberately tight. It is survivable if the crew moves well and wastes nothing.
Don't announce the timer to the players. Let the pressure build through description โ ships repositioning, voices on Den Den Mushi in the distance, the harbour traffic clearing as civilians get out of the way. They should feel the window closing without knowing exactly how long they have.
Finn. He was at the wheel before the second horn finished. He already has the route out of the harbour in his head. He has had three possible routes since they docked. He picked the best one forty minutes ago. His Sharingan eyes are reading the currents in the harbour water. "I know how to get out. Tell me when the ship is ready."
The submersible dive requires a minimum 10 minutes of active crew preparation. Rigging retracted, hatches sealed, pressure systems engaged. Bon must be actively managing the systems throughout. This cannot be shortened. It can be complicated by external interference โ every Marine action against the ship during prep adds time or creates a failure point.
The Prep Sequence
Everyone Has a Role
This is the first time the post-timeskip crew operates as a unit under pressure. Use it. Each character's timeskip growth should be visible in how they handle their role during the prep.
Minutes 1โ2
Bon begins the conversion sequence. He knows every system intimately โ he rebuilt the rig, he understands the hull better than anyone. His hands move without hesitation. Anisa is at the secondary controls giving him data. This is what 18 months of preparation looks like.
Minutes 2โ4
Kaillou plots the dive route. Not the harbour exit โ the route after. 200 fathoms down, Fishman Island bearing, current map from the Silent Meridian knowledge he brought back. He is faster at this than he was before. Significantly faster.
Minutes 3โ5
First Marine contact. A patrol cutter enters the lower harbour. Atsusato handles it. He doesn't fight the ship โ he removes the ability of the crew to operate it effectively, precisely and quietly, in under two minutes. The cutter drifts. Nobody died. The clock continues.
Minutes 5โ7
Migo covers the dock. Three targets โ Marine spotters on the upper platforms who have eyes on the Miku and are reporting her position in real time. Three shots. One breath between each. All three Den Den Mushi go silent simultaneously. The Marines lose visual confirmation for approximately 8 minutes. That's enough.
Minutes 7โ9
Second Marine contact โ heavier. A proper warship now, entering from the Grove 55 channel. This one is too large for Atsusato alone. This is the crew's test. Jimbo holds the dock. Manju holds the other approach. Chloe keeps the prep crew moving. Rokuji makes a decision about how much force to use and the answer is: just enough. Not more.
Minute 10
Bon calls it. One word. "Ready." The most important word in this session.
Rokuji โ the decision moment. At some point during the prep the crew could engage the warship properly โ fight it, disable it, make a statement. Rokuji says no. "We don't have time. We're not here to make a point. We're here to leave." This is post-timeskip Rokuji. He doesn't need to prove anything to Sabaody. He just needs to get his crew to Fishman Island.
"Ready."
Finn doesn't wait. The Miku moves before the word finishes. She moves like she was always going to move โ like the harbour was designed around her exit and everything else is just waiting to get out of the way.
Behind you, Marine signals are multiplying. The blockade is forming at the harbour mouth. Three ships. Maybe four. They know where you're going. They know what you need โ open water, depth, a dive window. They're trying to close that window before you reach it.
The Run
Finn's Conditions
Finn needs one thing to get them through the blockade: a gap. Any gap. He can thread through a space that no other helmsman would attempt at this speed. What he cannot do is make a gap that isn't there.
The crew's job for these 3โ4 minutes is simple: give Finn his gap. Migo picks off the rigging of the closest blockade ship โ suddenly it can't maneuver. Kaillou calls a current surge that pushes the second ship two degrees off course. The gap opens for approximately eight seconds.
Finn โ the gap moment. When the gap opens, everyone on the Miku feels the ship change. Finn reads the current, reads the momentum, reads the exact trajectory. The Sharingan eyes track everything at once. This is what the Gravewake Routes built โ not a helmsman who reacts to chaos, but one who decides it.
The Miku hits the gap at a speed that makes the harbour water flatten out behind her.
For three seconds you can see the open ocean ahead. The sun is setting somewhere above โ you can't see it from down here in the lower harbour but the sky at the horizon is red.
Then Finn says one word:
"Down."
The surface transition is the most vulnerable moment. Five minutes. The ship cannot maneuver. Cannot fight. Cannot reverse the dive. The Marines know this window exists. If they have pursuit vessels in range, this is when they press. Make the players feel those five minutes.
The Transition
Going Under
The dive sequence is Bon's moment. He is managing a system he helped build, on a ship he rebuilt from scratch, doing something no standard pirate vessel should be able to do. Let him narrate what he's doing. Let him feel the ship respond to him.
The water comes up the sides first โ slow, then fast. The rigging is already down. The hatches are sealed. The hull groans once, deeply, as the pressure changes.
Through the portholes: green water. Then dark green. Then darker.
The sounds of the harbour โ the horns, the engines, the Den Den Mushi shouting โ cut off as if someone closed a door. The only sound is the hull. And the sea. And Bon's voice calling system readings that Anisa responds to in numbers that mean nothing to anyone else on the ship.
Sabaody disappears above you.
You're down.
Viktor โ the hull groan. The first time the hull groans under pressure, Viktor's eyes go to a specific junction point โ one he spent three weeks reinforcing in month seven. He watches it. It holds. He exhales. Nobody else noticed what he was looking at. Anisa did.
Jimbo. He is the only crew member who is completely comfortable. He is a shark fishman. This is his element. He stands at a porthole watching the water darken with an expression that nobody has seen on him before. He looks at home.
Smokey. He is not comfortable. He is a donkey. He expresses his feelings about the submarine situation at length. Nobody can make him stop. His voice is the only sound other than the hull for the first ten minutes of the dive. Eventually he trails off. The quiet after is its own kind of peace.
Depth Reference โ The Descent
0โ20 fathomsLight still reaches here. Green-blue. The Sabaody roots visible above if you look up.
20โ60 fathomsLight fading. The water becomes a specific shade of dark blue that has no name on the surface. Things move at the edge of visibility.
60โ120 fathomsNear-dark. The bioluminescence begins โ creatures that have never seen sunlight, carrying their own light. Strange and beautiful.
120โ180 fathomsDeep ocean. Full dark except for what glows. The pressure is audible in the hull. The crew feels it without being told what it means.
180โ200 fathomsThe Miku's operational limit. Here the ocean floor begins to slope toward the descent to Fishman Island. The Miku is as deep as she can safely go.
The Passage
What Happens in the Dark
The dive takes approximately 3 hours at operating depth. This is deliberate pacing time. Use it. These are nine people who have been in their separate crucibles for 18 months and are now locked in a tin hull together in the dark. Some of the seeds from the reunion can stir here โ not resolve, stir.
Small moments for the passage:
- Someone finds Viktor's gifts that haven't been opened yet. Maybe now is when they get opened. One of them lands slightly wrong. That conversation starts here.
- Manju stands at a porthole and her reflection in the dark glass shows the faintest crimson edge to her eyes. Chloe sits next to her and doesn't ask yet. Just sits there.
- Rokuji finds the manifest. He reads it. He sets it down. Viktor, across the room, says nothing. They both know the conversation is coming.
- Kaillou navigates by feel โ no instruments read correctly at this depth. He is reading the current the way the Tide Hermit taught him, eyes closed, hand on the hull. It works. That surprises him more than it should.
- Finn is at the wheel in silence. The chaos of Sabaody is gone. He is navigating a current system that no standard chart acknowledges. He is completely calm. That is new.
The Threat
The Ocean Isn't Empty
Somewhere around the two-hour mark, Kaillou feels something. Not the current โ something in it. Something large, moving parallel to the ship. Sea King. Deep-water variant, far larger than anything the crew has seen on the surface. It is not attacking. It is curious.
Let the tension build. Let the crew decide how to respond. Let Jimbo be the one who resolves it โ not through combat, but through presence. A shark fishman, in the deep ocean, meeting a sea king eye to eye through a porthole. A long moment. The sea king moves on.
Do not fight the Sea King. The Miku cannot fight underwater. That's the rule and the point. The crew has to solve this without their usual tools. That restraint is what this scene is for.
The Approach
What They See First
End the session here. Don't enter Fishman Island this session โ save that for the arc guide. End on the image of arrival. It should feel like surfacing into something, even though you're still descending.
Kaillou says: "There."
Below you โ and it takes a moment to understand what you're seeing โ there is light. Not bioluminescence. Not the cold blue of deep-water creatures. Light. Warm light, amber and gold and faintly green, rising from something at the bottom of the ocean that should not be there.
As the Miku descends the last thirty fathoms, the shape of it becomes clear. A dome. An enormous dome, ringed with light, sitting on the ocean floor like a city that decided the surface was optional.
Through the porthole: towers. Streets. Ships moving in the water between structures. Life โ an entire, complete, impossible life โ at the bottom of the sea.
Fishman Island.
You made it.
"The impossible routes exist.
You can read them.
Now go find the ones no one else can."
โ Grim Tempest ยท Sabaody ยท To Kaillou
End here. Don't dock. Don't begin the arc. Let Fishman Island be the image the players carry into the next session. The arc guide handles everything from the moment the Miku enters the dome.
- Prep time: 10 minutes minimum. Cannot be shortened. External interference adds time.
- Bon required: Systems fail without him actively managing. Incapacitated Bon = failing dive.
- Speed: One third of surface speed underwater. Cannot outrun purpose-built submarines.
- Depth limit: 200 fathoms hard cap. Below this risks hull implosion.
- Duration: 4 hours maximum. Auto-surfaces at the limit.
- Surface transition: 5 minutes. Fully exposed. Cannot maneuver or fight.
- Recharge: 2 hours after surfacing before next dive.
- Combat: None underwater. The Miku cannot fight submerged.
- Detection: Harder to find, not impossible. WG has undersea infrastructure.
- Commitment: Once begun, cannot be aborted. No half-dives.
The submersible system is a strategic option with real costs. It is not an escape button. Every dive should feel like a commitment the crew is making with full knowledge of what it costs them. If it ever starts feeling easy โ add a complication. The ocean is not safe. The Miku is not a submarine. Both of these things are always true.