Shipwrecked in Saltmarsh

Fianna

     Fianna focuses on staying afloat and on helping Kelnan not lose the box.  This was all for naught if they lose that...  ((In other words, I don't trust my rolls so will let Kelnan do it!))  If movement can be done as well as keeping the box afloat they will, of course, move away from the ship and towards the dwarven one which brought them here...

Successfully dodging tentacles, Dain dashes up the rickety deck, and away from the large-mouthed demons.
One, however, takes a parting snap at him:

Demon Bite Attack vs. Dain: 19 Hit: 11 piercing damage.

Even protected by Katernin's shield, Dain takes a nasty bite to his shoulder as he leaves. (I have adjusted his sheet.)

He attempts to grab Molo and sprint the remaining 25 or so feet up the sloped, rocking deck to the edge of the rail.
Dain Athletics check: 20

He successfully pulls his stunt off, and the dwarf and his kobold friend tumble into the ocean below.

Meanwhile, Fianna and Kelnan begin to swim with the box. They find that they can absolutely propel the box (up to 30'/turn) provided it doesn't slip into the depths. (Kelnan needs to make that DC 10 Strength (Athletics) check with advantage)

Katernin, Molo, and Kelnan may act next. (Kelnan is limited to swimming and rolling that save. If he wants to do another action, you can only travel 15' with the box.) 

Molo will keep trying to go help get the box

Kelnan puts everything into securing the cargo, pleased that the rest of the party has cleared the ship.

Athletics: 13

Kelnan and Fianna manage to hold onto the bulky box for another round, as they slowly make their way toward the approaching skiff.

Katernin may act next.

Katernin continues to dash toward the dwarven skiff on rapidly fading wings. (One more turn left!)

The demons are left to contend with the tentacles:
Demon 1: DC10 Dex Save: 16 or take 8 damage
Demon 2: DC10 Dex Save: 16 or take 7 damage
Demon 3: DC10 Dex Save: 5 or take 4 damage
Demon 4: DC10 Dex Save: 1 or take 5 damage

The fourth demon attempts to climb the stairs:
Demon 4: DC10 Strength check: 5

One of them scrambles forward (Dash) to leap into the ocean near Dain. Two more finish eating Krell's remains and then begin to traverse the sinking deck (but don't yet reach the rail.)

The vessel is rapidly sinking. 

Everyone may act. Molo, Kelnan, or Fianna must roll a DC 8 Strength (Athletics) check with advantage, or the box will slip from your grip. You may also move the box forward 15 feet as a group. Dain is within melee range of a swimming demon.

Dain:  Movement and Dash swimming towards the box / skiff.  Hell hope the demon isn’t a proficient swimmer and is crap attacking in water…

Fianna:  Seeing their pursuit, Fianna will entrust the box to Molo and Kelnan, the Mage Hand and Fi’Finella while she uses her action to send an Eldritch Blast at the closest demon… Movement still towards skiff though.

Eldritch Blast Attack: 12 Damage: 10

Kelnan hangs on tight and swims on.

Athletics: 10

Dain breaks away from the sinking ship and tries to catch up with the box. 
The demon, however, has other plans:
Demon Bite Attack vs. Dain: 11  Hit: 7 piercing damage.

Dain manages to keep the foul thing away. Unfortunately, he's not as fast a swimmer as the rest of you, and still has a distance to catch up.

Fianna lets go of the box and fires off a beam of purple plasma at the fiend. It narrowly misses the huge-mouthed monster.

Katernin may act next. (She can make it to the skiff, and still have an action; but her wings dissolve completely at the end of this turn.)
Molo's action (help) and movement are already determined, unless he has a bonus action or simple act to perform in addition. (Kelnan has already made the roll for the box for the round, but it presumes that you are helping.)

Molo, with Kelnan, continue to push the box through the water, even as the dwarven skiff approaches. (It's still more than one round away, and the DC of keeping the box afloat will increase a little next turn without Fianna's help.)

There is a blue flash and a commotion aboard the sinking ship as the two demons still aboard seem to be violently engaged with something.

Katernin is up.

Katernin lands on the boat with a heavy thud, her wings vanishing in the next seconds. She looks to the dwarfs, "What can I do to get us moving faster?"

((Movement: land on the boat. Action: help with rowing the boat))

Katernin lands in the skiff, just as her wings fade into the salty air.

She urges the dwarves onward, although neither she nor the dwarves know what she can do to accelerate the vessel. Persuasion: 8

The demon in the water catches up to Dain, but doesn't have an action left to attack yet.

~*~

Top of the round:  Everyone may act.

Dain or Molo needs to make that DC 10 Strength (Athletics) check with advantage. (DC 8 if Fianna rejoins them.) You will reach the approaching skiff next turn.

Dain is within melee range of the demon again, as it appears to be chasing him.

Kelnan recommends Molo take the lead in keeping the box afloat (on account of having a non-negative athletics skill and all) and does his best to assist and keep it moving toward the advancing skiff.

Molo heaves at the box to keep it afloat 

athletics 25 

Dain:  Movement and Dash Action again both put towards swimming towards the skiff.  Allows AoO but the demon would have an attack available when it catches up if Dain disengages and moves away.

Fianna: I assume the demon is within 90 feet now so Fianna will cast [/spell]Hex[/spell] on it (bonus action) and then follow up with Eldritch Blast

Eldritch Blast Attack: 21 Damage: 8 Plus 3 Necrotic damage from Hex.

Molo, hobbled on land but not at sea, stabilizes the big blue box with a mighty heave. It is safe from sinking for this turn. Molo and Kelnan (with the sustained help of Fi'Finella and the spectral mage hand) continue to propel it slowly forward.

Dain again tears away from the demon, but not before it tries to bite him again.
Demon Bite Attack vs. Dain: 23 Hit: 6 piercing damage.

 It misses again. The massive jaws cleave the air behind him as he swims as fast as he can toward the approaching skiff.

Fianna fires off a potent beam of magical plasma that hits the demon square in the mouth. It loses a few nasty fiendish teeth and much of one lip, but it still advances, badly injured.

The ship continues to rapidly sink. A film of grease and dead spiders and debris begins to spread across the rolling black swells, even as the massive tentacles continue to shatter the dying vessel. With a slight blue flash, there is stillness on the deck. The other demons are no longer evident.

(I will update the map tonight or tomorrow morning. Still on the road.)

Katernin may act next. She stands in the skiff, now wingless, trying to figure out how to speed up this rescue.

Did Fianna use her move to swim toward the skiff?

Katernin may act next.

(At the top of the round, Molo and Kelnan will need to roll one final save against losing the box before trying to get it aboard the skiff.)

(If possible, Kelnan would like to skip the save and Misty Step with the box onto the skiff)

     Yes, Fianna would have used normal movement towards skiff.