Though the fifth edition of the Dungeons & Dragons ruleset is due to be released this summer, I have given some though to trying my hand at a Pathfinder campaign.
In 1998 I started my first undersea campaign, “Beneath the Pinnacles of Azor’alq”, a first edition Advanced D&D play-by-post adventure. In 2007 I created “Heirs of Turucambi”, a 3.5e D&D chat-based game set beneath the surface of the Oljatt Sea on Oerth, the World of Greyhawk. I currently run this game each Sunday night.
Alluria Publishing has created a series of robust undersea supplements for Pathfinder, starting with the Cerulean Seas campaign setting. I would utilize these supplements, also available in printed and electronic formats, for my Pathfinder endeavors.
My current undersea game uses a simple chat interface, Internet Relay Chat or IRC. Should I run a Pathfinder/Cerulean Seas adventure, I would employ a more advanced interface, a Virtual Tabletop application called Roll20. Roll20 allows players to share a common screen, seeing a map of the adventure locale and simple game statistics combined with videoconferencing capabilities. I would use Roll20 in conjunction with Hero Lab, an interactive character sheet.
What would you like to see, in such a game?