Okay, so: this went in many ways much better than expected.
At the end of the previous session, the party had taken to boat by virtue of killing off everybody except for the captain (and the bosun, though he was only barely alive). They opened this session with the Chevalier trying -- and failing badly -- to throw the captain overboard, while murderchild did more stabitty-stabs.
(For those who aren't keeping track: murderchild is Raven, an adult halfling masquerading as a human child; the Chevalier is a human bard who came from a life of indolence and luxury despite not having any lands or money himself; Kane is the town undertaker, a human paladin intent on seeing the dead -- and those as need to be dead -- on their way; and Salty Walt is another human bard, a ship's shanty-man who sometimes masquerades as a captain and is haunted by a ghost-fish that only he can see.)
In the course of the fight, the bosun bursts back out of one of the aft cabins and promptly gets stabbed to death; the captain gets badly wounded and finally thrown overboard, where he disappears and presumably drowns; and everybody else is basically okay. There are still four sailors left from the original crew of the Sea Ghost, but they've rowed into the cave and disappeared; even if they turned back immediately, it would be quite a while before they could get to the ship. Still, Kane elects to remain on the deck and keep watch while the others explore the ship.
Almost immediately, they discover a secret compartment holding a shipment of well-made weapons; as they continue, they find a sea-elf who's been held prisoner by the smugglers. Continuing on, they discover... well, everything. The sea elf calls himself Oceanus; he and Salty Walt can converse in Aquan, and he and the chevalier can converse in... something else. Elvish? Probably.
In the main cargo hold they discover more silks and brandy casks, stamped with the royal seal; those are almost certainly stolen, and will need to be sold through the council to avoid the impression of the group being party to smuggling or piracy themselves. Somewhere in here, Kane calls down that the remaining sailors are on their way back to the boat; the group considers ramming their boat with the sea ghost, but realizes that they lack the expertise to do anything more than basic sailing. They can probably get the whole ship back to the docks at Saltmarsh, but maneuvering to hit a small boat in the dark? Not so much that. Instead, they grab oil and rags and use flaming arrows to set the docking boat (and at least one sailor) on fire. The first mate jumps out at the last minute and begins swimming; Oceanus taps the Chevalier on the shoulder and says "Dagger?" in Elvish until somebody hands him one. Then he dives over the side, a lean shape cutting into the water and disappearing; a few moments later, the First Mate abruptly disappears underwater too. Then Oceanus is waving at them from where he's holding the anchor chain, and they haul him up in the process of weighing anchor. ("We should keep him," murderchild decides.)
It turns out that the group isn't entirely alone on the ship: they discover a trio of lizardfolk in one of the forward cabins, engaged in a game of sticks. The Chevalier, an enthusiastic student of games of chance, recognizes this as something the slaves played in his former lover's mansion, and immediately gets himself dealt in; the lizardfolk are speaking a pidgin of common and draconic which the Chevalier can only partly follow, but they're happy to play against him. He tidily wins the first round, and they're impressed.
So while Salty Walt and Kane lower the sails and get the Sea Ghost underway for Saltmarsh, the Chevalier and murderchild have a lovely evening of gambling with the lizardfolk. Oceanus mostly just stands in the door and watches this. It turns out that the lizardfolk had cut a deal with the smugglers, exchanging chunks of electrum for well-crafted weapons and armor; it also turns out that they've recently returned to an abandoned fortress of theirs, only a few miles down the coast from Saltmarsh. Only, they have no plans to attack the town. They were driven out by the "shark-kin", a term which Oceanus identifies as Sahuagin. They're mainly interested in getting the the weapons to their colony, and only mildly concerned that the boat is heading the wrong way for that.
They get close enough to the docks for somebody to row out and tow them ashore, and that's more or less where we ended the game.
Somewhere in the middle of all this, we attempted to play music at each other; this was not the right environment for it, and in any case it turned out that nobody had a suitably metal version of Drunken Sailor on hand, so we wound up substituting Queen's Fat-Bottomed Girls for pirate music instead. Which, y'know, works fairly well.
But in the interest of having these things available:
And hey, as a bonus: