The Second Channel
The Second Channel
Read aloud
A stake bearing a branching mark stands at the reef's edge, half buried in weed and mineral crust. Beneath it, warm water breathes out of a flooded opening, carrying a slow knock that you feel in your teeth. Maite offers you an air bell and asks you to find out where the old channel goes.
Run the session
Cheat sheet
Objectives
- 1Locate and enter the second channel.
- 2Navigate the flooded tube without losing the party to its current or lack of air.
- 3Learn who has maintained the old route and what has recently changed.
- 4Bring the expedition to the lower threshold and choose what to do next.
The clock
The party's air supply limits each underwater leg. After the air-pocket scene, advance the local expedition clock by one day. If the Tide-Lock seals and the party takes the flooded detour, advance it by another day. At the ladder, a DC 12 Intelligence (Investigation) check estimates that the knock arrives about once every ten heartbeats and is gradually speeding up. The party has hours, not days, before the next stage demands attention.
Scenes
- 0:00The Air Before the Dive
- 0:45The Mouth and the Narrows
- 2:00The Air Pocket
- 3:15The Light
- 4:55The Ladder
Cast
- MaiteQuestgiver and practical rescue ally
- IstvanInterested ally and optional patron
- TomasWitness and keeper of local channel knowledge
- OlinWitness and diving support
The hook
Set the scene
At the reef's mouth, old stakes emerge from the water like broken fingers. Mineral crust roughens their surfaces, and the carved branching mark on the stone lintel catches the lantern light. The water spilling from the opening is warmer than the sea around it. With each distant knock, the stake gives a faint, dry vibration beneath the party's hands. Maite checks the seals on the borrowed air bells while the tide draws weed across the entrance.
How Maite asks
Maite approaches the party at the reef-side staging point with air bells, a hooded lantern, and a request for a cautious survey.
She stresses that retreat is acceptable and that no one should spend their last breath proving a point. Istvan may separately offer payment for a marked stone if the party has already heard about his interest in old routes.
Rumours
Scenes
about 6 hours0:00
45 min
socialThe table is here
1. The Air Before the Dive
A reef-side staging point at Kelpstrand, with wet rope, salt-stiff gear, and the smell of kelp in the air.
Present the request, review air and light plans, and establish that rescue and retreat are possible. Let the party decide what equipment and support to take before entering the water.
NextWhen the party has checked its gear, the tide pulls away from the branching mark and opens a dark slot in the reef. Follow them as they slip below the surface.
0:45
75 min
exploration
2. The Mouth and the Narrows
The flooded mouth and a tight tube 20 to 40 feet below the surface. Pressure is not a hazard at this depth; breath and visibility are.
The party finds old stakes and the branching mark at the entrance, then squeezes through the Narrows where warm water pushes against the current. Telegraph the danger with the mineral-crusted walls, faint flashes ahead, and signs of feeding before the swarm attacks or withdraws.
The NarrowsNextPast the tight passage, the water opens into a pocket of air. The party's lantern catches on a dry ledge, where a familiar knot waits among scraps of rope.
2:00
75 min
social
3. The Air Pocket
A dry ledge above the flooded tube, with an old rope coil, waxed lantern, and handholds worn into the wall.
The party rests, finds the net-mender's needle and cord, and can meet Tomas as he surfaces with a coil of chain. Treat the exchange as a chance to build trust. Showing the cord or ledger earns his full account without a check; threats or a revealed lie carry consequences.
NextAfter the party has rested and Tomas has said what he is willing to say, let one day pass on the expedition clock. The route beyond bends toward a blue-green glow.
3:15
100 min
exploration
4. The Light
A low chamber with glowing kelp, fitted stone underfoot, warm water, and a salt-white bench. The water's green-blue light makes red crust along the walls stand out.
The party enters the kelp-lit chamber, where well-kept tools bear harbor marks. A careful search can find the Halden ledger beneath the bench. Red residue and the warmth against the current foreshadow the drake, which waits by the tools unless detected, calmed, or avoided.
The Light ChamberNextBeyond the chamber, a rusted ladder drops through a hole in the floor. Each knock shivers through the rungs and travels up through the party's hands.
4:55
60 min
exploration
5. The Ladder
The far end of the kelp-lit chamber, where a rusted iron ladder descends into warm water and the stone trembles with each measured knock.
Let the party estimate the knock's pace, inspect the ladder, retrieve an optional route marker if applicable, and decide whether to descend, turn back, or report. The pulse is speeding up, but the party has time to make a choice rather than being forced into a blind plunge.
NextAs the party commits to its next move, the knock lands again through the ladder. End the session with someone reaching for the first rung, turning toward the way back, or calling the others to listen.
Behind it
What people believe
An old route beneath Kelpstrand's reef has begun carrying warm water and a steady knocking sound.
The party is asked to explore the flooded passage, record what remains of its old markers, and learn whether the route can be safely used. The water is not deep enough for pressure to be the main danger, but breath, light, and the way back matter at every turn.
Background
Beneath Kelpstrand's reef, an older channel survives where modern charts show only stone.
Its route was maintained by the Halden family, whose keepers quietly tended a gate and left marks for those who knew how to read them. Recently, warm water has begun pushing the wrong way through the passage, and a measured knock sounds from deeper below. This expedition reaches the old route's lower threshold, where evidence of careful maintenance meets signs of a new disturbance.
The stakes
A careless dive can cost time, equipment, trust, and access to a vital old route.
The expedition's discoveries may expose generations of private maintenance and draw the local council into a dispute over who controls the channel. At the ladder, the party hears a measured sound whose source remains unknown.
Encounters
3The Narrows
combat
A cramped, mineral-crusted underwater tube with a warm countercurrent, a cracked crystal seam, and cold stone near the far lintel.
Foes
Siphon-Mite Swarm
ComplicationThe narrow passage is shoulder-tight, with slick mineral crust and a current pushing against the party. A character can squeeze through with a DC 12 Strength (Athletics) check, or recognize that the mites avoid the colder stone near the lintel with a DC 13 Intelligence (Arcana) check. A cold lamp, cooling jar, or cold brine can drive the swarm away without a fight. The swarm targets the first spellcaster it notices, or a carrier of a magic item if there is no spellcaster. It cannot pursue beyond the tightest section.
ScalingDesigned as a low-to-moderate threat for four 2nd-level characters. For a smaller or depleted party, have the swarm withdraw after one round of feeding or when it takes any damage. For a stronger party, add a second round of pressure from the current rather than adding another swarm.
The Light Chamber
combat
A low, flooded chamber lit by glowing kelp. Red-crusted stone, fitted flooring, a salt-white tool bench, and narrow exits limit movement and visibility.
Foes
Glassblush Drake
ComplicationThe drake is visible if the party studies the red residue and warm water before approaching the tools. A DC 13 Wisdom (Perception) check spots it in time to avoid surprise. A DC 12 Wisdom (Animal Handling) check or an offering of food can calm it. It flees once bloodied. The ledger and tools remain recoverable if the party drives it off, calms it, or waits for it to leave.
ScalingDesigned as a low-to-moderate ambush for a 2nd-level party. For a cautious or inexperienced group, use 30 hit points and have it flee once reduced to 11 hit points. Avoid increasing its damage; this scene's danger comes from surprise and restricted visibility.
The Silt-Den, optional
combat
A collapsed side-tube with a cracked nesting ledge, pockets of silt, and a narrow passage around the den.
Foes
Giant Octopus
ComplicationThe octopus guards eggs in a crack and does not initially hunt the party. If a fight begins, struggling clouds the water and reduces visibility to 10 feet for 10 minutes. The octopus uses its ink to retreat when bloodied. Three pearls are lodged near its den; taking them without calming it draws its attention.
ScalingOptional side encounter. One giant octopus is a modest threat for four 2nd-level characters. The party can avoid it with a DC 12 Dexterity (Stealth) check, calm it with a DC 12 Wisdom (Animal Handling) check, or offer shellfish. Omit the encounter if the group is low on resources.
Cast
4Maite
QuestgiverQuestgiver and practical rescue ally
WantsMaite wants the party to investigate the route without losing anyone to an avoidable dive. She will lend an air bell and help recover anyone who becomes incapacitated in the water.
“Take the air bell, and keep its mouth pointed up when you can. If the water starts knocking back, do not waste breath arguing with it.”
Istvan
Interested ally and optional patron
WantsIstvan wants evidence that an older route was deliberately blocked. He is interested in the marked stone near the air pocket and will offer payment for its recovery.
“That mark belongs on a chart, not under a reef. Bring me the stone if you find it, and I will pay for proof.”
Tomas
Witness and keeper of local channel knowledge
WantsTomas wants the old gate kept safe, his family's quiet work treated with care, and someone else to share the burden of hearing the knock. He will explain more if the party approaches honestly or shows him the cord or ledger.
“I kept the gate because somebody had to. I did not know what was on the other side, and I am tired of pretending that does not frighten me.”
Olin
Witness and diving support
WantsOlin wants the party to establish whether the lower passage is safe enough for future rescue or salvage work. Olin can lend an air bell and will share practical observations, but does not know the route's full history.
“The fitting was not there the last time I came through. I left the room tended, and now the water has a taste like hot pennies.”
How it ends
Rewards
Items
A maintained set of harbor tools: hammer, chisel, chain, and sharpening stone. They are useful working equipment, not magical items.
A waxed lantern and a coil of old rope from the air pocket, if the party chooses to carry them.
The Halden ledger, valuable as evidence and local history rather than as a trade good.
On a win
The party reaches the rusted ladder with enough information to understand that the passage was used and maintained long before modern charts recorded it.
They can return with the ledger, tools, marker, or a firsthand account of the changing knock. On reaching the ladder, the characters gain a milestone and advance to 3rd level, whether they descend immediately or return to prepare.
What it leaves open
If it fails
- The party fails to open the Tide-Lock before it closes.
- The sealed door costs time and air, and the party must take a longer route. They still reach the air pocket, but the campaign's local clock advances by an additional day.
- The party threatens Tomas, exposes him carelessly, or lies about its purpose and is later found out.
- Tomas shares necessary facts only under pressure and refuses to assist at the next gate. The party loses his practical advantage, but his knowledge can be reconstructed from the Halden ledger.
- The party enters the flooded route without enough air, light, or a retreat plan.
- The party loses time and may need to retreat to the air pocket or surface. Maite or Istvan can retrieve a character who reaches 0 hit points from drowning, so a failed breath plan creates a rescue and delay rather than an automatic death.
- The party leaves the Light Chamber without finding or preserving the Halden ledger.
- The party can still reach the ladder, but has no confirmed record of who tended the route or how its gate was maintained. The next expedition begins with less reliable information.
Complications (d6)
- 1A school of silver fish bolts through the passage, briefly obscuring the party's view. The next character navigating the route must succeed on a DC 11 Wisdom (Survival) check or spend a minute finding the correct channel.
- 2Glowing kelp flickers in the rhythm of the distant knock. Until the party moves beyond the next station, sound-based communication is difficult and verbal coordination underwater is unreliable.
- 3A fresh five-fingered print in the silt has a missing thumb. A DC 12 Wisdom (Perception) check notices the mark is recent and points toward a side crevice, where the party can find a useful handhold or lose a minute investigating.
- 4The water turns warm, then abruptly cold. Each character using an air bell must check its seal; on a failed DC 10 Dexterity check, the bell loses one minute of usable air.
- 5A pale crustacean darts from a crack, carrying a small metal fastener. Recovering it takes a minute and yields a serviceable replacement part for a damaged tool or lantern.
- 6The water falls unnaturally still for several heartbeats. The next knock arrives through the stone, strong enough to shake loose grit and make the route ahead briefly hard to distinguish.
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