Everything I've found about aquatic campaigns would suggest that they are inherently more difficult than traditional campaigns, for the GM and player both.
The Rules Difficulties
For one thing, there are more rules for underwater play. This, of course, means even more things to keep track of than normal. These are the rules I'm referring to. Most of them really just serve to limit the game even further, without really adding much. As an example, it makes fighting at range highly difficult, if not out right impossible. In exchange, ranged fighters gain no benefit at all, nor is any additional potential combat style added to make up for it.
However, even though it limits the potential options, the additional rules still don't answer all my questions. Ex.; Does depth have any effect? Do tropical vs. arctic waters have any differing rules?
Not to mention the fact that Pathfinder, being a game built around the concept of 2D movement, really doesn't flesh out the rules for a 3D environment very well, which an Aquatic campaign would have to be by necessity.
And, finally, it limits the options that the players have. Obviously, they would have to play as an aquatic race. I know of three, and outside of being amphibious, none of them are all that interesting. Beyond that, it also makes playing certain classes harder-spell casters in particular coming to mind-as well as restricting animal companions and the like to only those things that can survive under water.
What's the Benefit?
All of that said; Is it worth it? Again, I've never played in an all-aquatic campaign. Have you, and what's the payoff that makes it worth the difficulties I see? Is it an acquired taste, so-to-speak, or is it one of those things that you should do once for the experience, but never again? Or perhaps it's something that just really isn't worth all the hassle? I'm looking for answers from experience, please and thank you.
The reason I'm asking all this is two-fold. For one, having never played in such a campaign, I'm wondering if there is some aspect of the game-type that I'm missing that makes up for all the issues I've stated.
For two, the group I'm currently taking part in (none of which have played in such a campaign, either) is considering playing in such a game, and unlike most other situations, I (the traditional voice of experience in the group) have no advice to offer them about it.
Best Answer
I would love to hear from someone who has played an aquatic campaign. What follows is simply my observations about what upsides the rules offer:
3D Tactics
Melee Heavy
Because ranged weapons are restricted, closing to melee will likely happen even more than in a standard game. Because the majority of statted monsters are best at melee, this adds to the challenge, letting the monsters make use of their potent abilities more frequently.
Thrown or dropped weapons will not simply sit on the ground, waiting to be picked up at the end of combat. Unless you're fighting at the depth where your weapons have neutral buoyancy, they will sink out of reach or possibly float up toward the surface. The same goes for corpses and loot.
Alien World