[MENTION=12377]77IM[/MENTION]
My favorite parts of DMing the previous campeign was probably the crazy stuff the characters got up to. One time while adventuring back to the tavern where they got their first quest the gnome bard decided he wanted to play some travel tunes and asked if he could roll for it, and I said sure why not. He rolls a nat 20, I ask him to roll 1 more time and he rolls another nat 20. I ask him to pick a number between 1 and 10 and if I roll that something wierd would happen. I roll the number he said and then I had to come up with something on the fly. I decided on having an awakened shrub coming out of the forest and dancing to the song. The party took a liking and adopted him, naming him Lord Leafy III. Later when they were with some dwarves sieging a city that was being occupied by ogres and a hill giant, they tried to intimidate them into surrendering. I didn't think it would be so bad, so I let them try, the bard and leafy played a haunting tune while the tiefling druid chanted in infernal and summoned black fire and the silver dragonborn barbarian stood on the front lines and roared. There were 2 nat 20s rolled on that check, but when I rolled insight to counter them I got a 3, but then as the hill giant got there I had them roll again. This time i rolled enough to beat them and the combat started. Near the end of the combat everyone but the bard and leafy was down and the hill giant was at 6 hp. Leafy who at this point had only helped during the intimidation check looked to his "father" and said I'm sorry. He scrambled toward the giant and in a last ditch effort attacks him. He crits and deals max damage to this thing dealing exactly enough damage to kill it. This then spread the legend of Lord Leafy The Giant Slayer.
Other than that I had them go into an arc of espionage, black market deals, and fight pits where they made some connections to the underworld and saved the dwarven government from a doppelganger crime syndicate. That was about when that 1 player had to leave, so the campeign wasn't super long lived but we still have some pretty good memories from that game that we still reference today.
This sounds amazing!
The reason I asked about your favorite parts of DMing, is that it's really important to make sure that you are having fun, because if you're not, it's very hard to run a good game. But if the DM is enthusiastic and energized, that usually bodes well for player fun. Since it was the players who suggested a nautical campaign, there's a risk that you might feel too uninspired.
If your favorite part of DMing is player hijinks, that's great. It means you need to give the PCs plenty of opportunity to do unexpected things. In general, this means presenting them with decisions where the "correct choice" is not at all obvious. For a nautical campaign specifically, here's what comes to my mind:
Isolated Islands. You know how, on every episode of Star Trek, they show up on a weird planet with some odd inhabitants and some thought-provoking science-fictiony thing? That works super well in a seafaring campaign, because each island can develop its own culture, magic, and "personality." Maybe the PCs want to avoid Wraith Island, so they wind up on Grung Island instead, and it turns out the grung are not such bad people, and would you like to take part in the 247th Annual Grung Games?
Cosmopolitan Port City. Well this is kind of the opposite; more like the cantina in Star Wars. Often in a naval region there will be a central trade hub where exotic individuals gather and scheme. This is a great way to introduce more interesting NPCs, and lets you run an urban adventure whenever you are in the mood for it.
Exaggerated NPC Personalities. This is a staple of pirate fiction AND it's a great way to prompt player hijinks. Some classics are: the salty old fisherman full of legends and tales; the ruthless pirate captain; the dashing honorable pirate captain; the wide-eyed swabbie; the greedy merchant; the intrepid explorer; the naive professor; the dainty aristocrat; etc. Then, you can also mix in all your favorite fantasy tropes: the reclusive wizard; the fast-talking bard; the mysterious assassin; the genial-yet-threatening head of the thieves' guild; the compassionate high priest; the stern guard captain; etc. If you've already run a game featuring espionage and doppelgangers, I feel like you could probably rock this part pretty hard.
Treasure Maps. Holy crap, few things motivate players like a good treasure map. Make it full of dilemmas though. What if X marks a spot right smack dab in the middle of hostile territory? What if it's underwater, guarded by a giant crab (and if you fight it, blood attracts sharks on round 2, etc.)? What if getting to the treasure or interpreting the map requires you to make a deal with an NPC, or work together with a rival?
Double Deals. A great way to instigate hijinks is to have NPCs who are enemies with each other, and both sides want the party's help. For example, smugglers vs. the harbormaster; both could be valuable allies. Pirate captains and crews often had fierce rivalries, that the PCs could get caught in the middle of. Maybe your new friends from Grung Island really, really don't want you to engage in trade with the residents of Serpent Island, but the Serpent Islanders pay really well...
Un-fightable Villains. This means, villains that you can't just run up to and attack. Bonus points if the villain doesn't really see the PCs as a direct threat. This way, the players can decide how to approach the villain issue, instead of reacting all the time. The sea-hag is a great idea because hags are manipulative, so I'd milk that for as long as I could. Krakens and aboleths are aquatic enemies that would hatch dangerous schemes, but aren't necessarily out to get the PCs in particular, and are kind of hard to fight. An evil storm giant would be pretty cool too. These are the kinds of bad guys that can send a variety of minions bubbling up to the surface. For non-aquatic villains, try placing them on islands that are surrounded by dangerous rocks. Maybe an old lich lairs in a floating pile of shipwrecks that moves about and is difficult to locate at sea.
Purposeful Exploration. Don't make the pirate campaign "about exploration." Instead, use exploration as a means to generate hijinks -- each discovery leads to a tangled knot of conflict, and the players must be creative to unravel it. And you can also use exploration as a reward; after the party uncovers the doping ring involved in the Grung Games, the grateful commissioners give them the directions to Solid Gold Island...
