Shipwrecked in Saltmarsh

Molo shrewdly scans the hold. He spots a crate near the stern marked with a stylized letter "A" - matching the description Aubreck gave for the crate he hired you to find. It is near the stern, about fifteen feet forward from the ladder, and roughly 35 feet from Molo. Swimming, he is unimpeded by his bad foot (~15' swimming speed.)

Molo calls up the hole. 

“Oi! Found Aubreck’s box! Drop a rope.”

     Fianna will help Dain tie off a rope and then lower it (and the party) down to the bottom of the ship.

Fianna helps Dain tie a rope around the nearby mast, and lowers it down. You may each climb or descend the rope as you wish.

Katernin keeps an eye out for anything trying to sneak up on the party.

Perception: 19

Molo tries to get the rope tied around the box, before heading up to pull it out.

Molo pulls one end of the rope aft, swimming through the murky, debris-filled water. He has just enough slack to tie a pair of loops securely around it. It's a big, bulky crate; it's rotten from months of being partially submerged in seawater. He hopes it will hold together long enough to extract it. He can hear the swells booming against the side of the hull. The water is oily and foul-smelling.

Above, Katernin keeps watch, while the rest of the party looks down into the dark, sloshing hold, waiting for Molo to return or call out.

As soon as the rope is looped tightly around the chest Dain will begin to haul it in.  He will do so slowly, trying not to put the chest through too much acceleration, so that the force upon it is minimal.  If Molo shouts to pause he will, instantly.

Kelnan

Upon news of the heavy chest, Kelnan tries to find a position of relative safety, produces his spellbook, and begins a ritual to cast Floating Disk.

"If you can haul it up, this will make carrying it easier and keep hands free in case any spiders appear. Give me a few minutes..."

     Fianna helps with the slow pulling of the rope, Fi’Finella is still playing lookout and watching for boogies and monsters…

The box is big and heavy and fragile - it's in poor condition. Dwal and Fianna begin to slowly haul it back, guided by Molo. It's slow-going. Katernin and Fi'Finella keep their eyes peeled for threats.

And Katernin suddenly spots one. Just ripples and movement emerging from the fetid waters in the hold below. Everyone else misses it, even Molo and Dain, who are closest. 

Corpses, animated, emerging from the water and cutting off Molo from the hatch. (The box is about halfway.) They lunge aggressively at Molo.

Initiative:
Waterlogged Corpses: 20
Fianna: 17. (Surprised, pulling rope behind Dain)
Katernin: 15
Kelnan: 5 (Busy, in other room)
Molo: 14 (Surprised, in hold)
Dain: 17 (Surprised, pulling rope)
Fi'finella: 12 (Surprised)

Katernin may act first. 

Katernin approaches the hatch and summons her spiritual weapon - the spectral vine that she conjured earlier - and lashes out at the corpses visible through the hole

Spectral whip attack vs. corpse #4: 20. Damage: 11
By getting on her hand and knees (prone, but in this case not at disadvantage) she is able to swing her handaxe at it as well:
Handaxe attack vs. corpse #4: 15. Damage: 5

 She manages to inflict a couple of gruesome-looking wounds to the corpse on the port side, but it shrugs them off. (It is somewhat injured, but not critically so.)

Her attack does, however, catch the attention of two of the foul-smelling creatures. Being somewhat taller than Molo, they can jump and reach the legs of anyone near the hatch - like Katernin and Dain. But they are now within melee range.

The other two pounce on Molo:

Corpse #1: Bite Attack vs. Molo: 7  Piercing damage: 10
Corpse #2: Claws Attack vs. Molo: 22  Slashing damage: 10 (and, on a hit, a DC 10 CON saving throw...)

Molo receives a vicious bite. Everyone but Kelnan may act next.

Initiative:
Fi'finella:   22 (keeping watch)
Dain:         15 (pulling rope, next to hatch)
Fianna:     13 (pulling rope behind Dain)
Katernin:    8 (prone next to hatch)
Molo:          7 (in hold with box, getting bitten)
Waterlogged Corpses: 5 (two snacking on Molo; two distracted by Katernin)
Kelnan:       4 (Busy, in other room)

Kelnan, though preoccupied by his spellcasting, certainly hears the commotion and is keeping an ear out for any indication his help is needed.

     Fianna quickly scans about for the thickest, sturdiest looking beam she can find and tries to tie off the rope around it, tightly, so as to not loose and progress of hauling up the crate if possible...

Kelnan was just a couple of minutes into his ten-minute ritual when the fighting broke out. (He can still decide what he wants to do at the end of the initiative; for now, he continues with the ritual.)

Fianna and Dain had already tied the rope to the mast before Molo found the box, so it's already secured; there's just a lot more slack now that they've pulled the box almost twenty feet. Dropping the rope won't affect that progress. Fianna may still act. 

Oh, ok...

     Fianna would then have Fi'Finella fly down into the hold invisibly and scout out how many zombies in total there may be... And for her part she shoots of an [spell]Eldritch Blast[/spell} at whichever one she can see from her vantage point - 3 or 4?

Eldritch Blast Attack: 8 Damage: 6

Molo spits some of the blood spurting from his wounds out at 1,2 and 3 casting bane 

DC 14 Cha save

Fianna fires her beam of colorful plasma at corpse #4, but misses; they are hard to target through the hatch.

Molo, badly injured by the bite, casts his dark enchantment. ( DC14 Saves: 8,  18,  3 )

Katernin and Dain may act next.

Dain drops prone and tries to swipe madly at one of the undead bodies below him.

Action: Reckless Power Attack versus creature #3: Attack: 3 Damage: Unable to parse dice roll.
Bonus Action (if he kills #3):  Reckless Power Attack versus creature #4: Attack: 19 Damage: 26