Crashing the Sea King's Party in a Yellow Submarine

Imagine this underwater

Our 5e Land of Azurth campagin continued last night with the party hearing a desperate plea for aid from Old Freedy, the kaleidoscopic tophat-wearing frogling ambassador from the Land of Under-Sea. It seems the utopia of Under-Sea has been overrun by the evil toad people from beyond the Blue Wall. Kully's father, Cory, and the cat-man Calico Jack were in Under-Sea at the time and are now aiding the froglings in finding champions.

The party quite reasonably wonders what they can do against a toad people army. Old Freedy explains that their are not actually that many toads, but that are too tough for the froglings to handle. The party was suggested by Cory Keenstep and Calico Jack (who had heard of them through his sister, Calico Bonny). Freedy discloses they have hired the party's old friend, the steam-powered  Commodore Cog to command the submarine craft they brought from Under-Sea.

This is all pretty incredible, but the most adventurous members of the party are eager to do it, and they overrule the more strictly avarous members. The first step (Freedy now reveals) is rescuing Cory Keenstep from the Sea King's folly. It seems he beat the libertine old merman in cards too many times, and the King won't let him go until he has gotten his money back.

The party traveled down a tube of airy water to the Sea King's palace. Only the female members were allowed inside by the sahuagin guard. They learn that the Sea King is sulking in his sanctum to avoid his ex-wife Cecaelia, who had taken over the second floor lounge. She was monopolizing Cory's attentions there. On a tip from some sea elf party-girls, Shade drugged an octopus body guard so that the males in the party could sneak in the back door. Unfortunately, the sahuagin and his four sharks caught them in the act and a bloody underwater melee ensued. The party was victorious, but at least 3 were seriously wounded.