"Just a moment, want to make sure we got them all." Sasha says and dives/jumps into the bilge water, diving around for a moment, looking for stragglers. Unless she finds any of them still alive she then hands the dead rats to someone still above. "Make sure to use these for Pluggs dinner now Arloch." She says with a smirk before coming up again.
She then heads to the main deck again, presumably together with the others, reporting to Mr. Plugg. "Rat infestation taken care of, was there anything else?"

Sasha Investigates the Bilges:  1

Sasha,  This is the first you have been down in the Bilges.  It is foul, and damp.  Thick with cobwebs hanging above the water that probably shouldn't be quite this deep.  There is a single bilge pump near the stern that presumably Jakes was manning before he was attacked.  The bilges also apparently double as the ship's brig.  6 sets of manacles are fixed to the bulkheads in the forward part of the deck.

Floating in the bilge water is a good degree of refuse, as some of your fellow crew members appear to consider this deck their personal wastebin.  A number of discarded crates and boxes packed with stray lie stacked against one wall.  One of the crates has been chewed through.  Apparently the rats wee stowaways until the heat of the day drove them out into the cabin.  It is unpleasantly warm down here and the humidity is even higher than it was out on deck where some fresh air flowed.  It has the feel of attempting to breath through a wet blanket.

As you look for any additional rats you do come across a few items that might be worth something to someone...you find:

a suit of leather armor
3 maces
a money pouch containing 12 silverpieces

Excited by your finds you continue your search, but are interrupted by a growling sound...you pause for a moment, trying to acertain what direction it came from.  Just as you are about to turn to call to the other crew members with you another pair of the rats swims out of a pile of refuse and attacks you!

Rat 6: Attack: 10 Damage: 4
Rat 7: (Pack Tactics) Attack: 22 Damage: 5

And now we can roll for initiative!  There were a total of 7 rats...with where I had them arranged 5 could be seen from the hatch after the thunderwave.  These two cannot be seen from the lower deck...so to attack them at range you have to at least stand on the rope ladder in the Bilges...if you are not down on the ground I am going to say the attack would be at disadvantage just for the awkwardness of making an attack while hanging from a rope ladder.

With just 2 rats left you guys should make pretty quick work of them.  Good job resolving the bulk of this encounter in smart and strategic ways.

Rat 6 Ini: 12
Rat 7 Ini: 5

Initiative: 8.

As Sasha dives in, Vireil comments: "It would be much simpler to climb halfway down and look from there. And, if it's too dark for you Humans to see, I could-" However, as she's interrupted by Sasha's call for help, she stops her sentence and nocks an arrow into the bow, waiting for something to come into view.

"Alright, two more." Sasha calls out before the rats attack. She deftly avoids one but the other sinks it's teeth into her arm making her grit her own in pain.
Sasha initiative: 11

Sasha, you and Rat 7 are exactly tied...so I am going to do a roll off to determine who goes first.  Honestly I expect both rats to be dead before it matters...but just for book keeping purposes.

Rat 7: Sub ini: 7
Sasha: Sub ini: 65

Ringer Init: 8

Arloch's Init: 7

Arloch may not be pleased by the smell of the bilges but he is more than prepared to enter the murky water. Now knowing there to be two more rats below them though he hollers back to Sasha, "Don't worry! We're coming down!"

"No hurry, take your time." Sasha shouts from the bilges.

(dramatic tension...will anyone roll higher than 10 on their initiative?  or will rat 6 get to attack Sasha again before anyone can react?  Join us next time!  Same Rat Time!  Same Rat Channel!)

Grath Initiative: 21

"Are you alright? That seemed a bit nasty. Those really ganged up on you." Asked Grath, anticipating a sort of "Yes, it is fine" with a tone of "Damn, this hurt. We really have to pay more attention to pests around here"

(with that initiative you get to act before Rat 6, which is what is important.  Going to flip a coin to determine if you end up hitting 6 or 7 (since you have no way of knowing one is going to act first.  Honestly it would be more optimal if you do hit rat 6.  That damage roll is going to kill whichever rat takes the orb.)

Grath attacked rat #6!

The rat that had missed its attack on Sasha is suddenly struck in the ribs by an orb of fire about 2 inches across.  The burning smell of hair and innards fills the deck.  On top of everything else it makes the smell truly noxious.

(Rat 6 is down for the count...this means that everyone else gets to act before rat 7.  Finish that rat off!  Since you are all acting before it initiative order doesn't really matter, whoever posts first gets first swing at it).

Jonah takes careful aim, and lets a crossbow bolt fly, (assumedly) spearing the rat straight through the neck, pinning it to the inside of the ship's hull.

(Attack 20, damage 10)

(Yep, that will do it. Rats are dead. You guys are free to return to your duties. Or not.  Whose to say how long this task takes you right? If there is anything you want to do below decks now might be a good opportunity.)

Grath doesn't really want to go back to his duties, so he offers to explore the area for other "aberrations" below decks. After all, we don't want to get into another mangling situation like the one just transpired.

As the party starts to walk back (or not) to their respective posts, Grath goes to Plugg and says "I am assigned to repair duty. If you don't mind I will go below decks to check and fix the hull, compartments and what not down there. I will also look for some holes and damage where these stowaways might have slipped in."

"Thanks, good job, I think those were the last ones, now help me up please." Sasha says with a smile. Unless anyone grabs any of the stuff Sasha found down in the bilges she sees to it that it gets to Cut-Throat Grok before seeking out Sandara. "Ehm, had a little altercation in the bilges with some stowaway rats. Any chance you could ask the Pirate Queen for some help with this?" She says, showing Sandara her bleeding arm.

Ringer will hold up his hands as his co-conscriptees make for the ladder up after being sent down less than a minute ago. He holds his hands up beside his eyes, thumb touching fingers, then opens his hands and widens his eyes, turning his head around to sign that they should look around while down here.

He then produces a soundtrack of squeaking, splashing, clanking and the like, so anyone listening will hopefully think that they are still fighting off the rats.

(Ringer suggests investigating the bilges further...One character can roll with advantage or two can roll seperately...Some of you still have GM inspiration you could use...or Ringer could whistle you a little ditty for Bardic Inspiration if he wants to).

Thought Sasha already had but if there are things she hasn't searched yet she will.
Investigation, with help (?): 20 + Bardic inspiration (?) 5

((Sure, bardic to Sasha. He's also suggesting that we underplay our abilities a touch, if we roll in and roll out in under a minute, largely unscratched, undirtied, with rats showing signs of magic having blasted them apart... With rat corpses hauled out, Ringer will cut off any charred bits, stick a few bolts in them, smear some blood about, etc. He'll demonstrate that he can magic the blood and grime away for anyone not keen to get on board with his deception.))

Sasha, you find a smaller crate tucked behind the grain crate the one of the rats that attacked you was hiding in.  Inside you find a few items of nicer quality than what you had earlier found in the bilge water in general.  Once you get the crate open you find a short sword in a silver sheath with ornate filegree on the outside.  You slide the short sword out of its sheath to check the edge of the blade and find that it is magical in some way.  A silvery light emits from the blade, pushing back the shadows of the dimly lit bilges.  You also find:

A bundle of 20 arrows with arrowheads on them that look a little different

a vial of clear liquid with a label that has been worn away with time.  The cork stopper in the top of the vial bears the symbol of Besmara (a skull & crossbones)
a money pouch containing 18 gold coins
a large glass jug that appears to contain a viscous oily liquid.  As you lift it the liquid inside moves of its own accord regardless of how you tilt the jug.  One tendril of the liquid reaches up and pushes against the glass stopper that is held in the top by a metal rod.  It is hefty, weighing about 15 lbs.

(imagine a bottle like this but with a metal pin going through the neck to prevent the glass stopper from being removed unintentionally.)

On visual inspection you can attempt a DC15 arcana check to see if you recall anything about what is in this glass jug.  (You know what...I am going to roll that just to keep things moving...Sasha and Jonah consult together about the glass jug and...)

Arcana 25

You are fairly confident what is inside is a Gray Ooze, though how someone coaxed an ooze into a bottle is anyone's guess.  It is smaller than ones you have read about so perhaps it is not quite as dangerous, but they are known for having a prodigious appetite for anything metallic.