"Arms in, head straight. Don't move, and try not to scream. Clock in once you hit the ground. Good luck."
~Safety Statement for The Drop, Doherty Outreach Center
Super Short Version: There are floating islands surrounded by a ring of freakish storms for 2000 years. On one of the islands is a humming obelisk that no on can explain. A government organization built an elevator to get people down to sea-level and explore the ocean. One of these explorers found another obelisk, and now everyone is trying to go out and explore the world to find out what the hell is going on.
Read on for more detail.
The idea here is that there are 5 floating islands surrounded by a freak ring of storms. No one knows where they come from, only that they make travel to the rest of the world impossible. It's been that way for about 2000 years.
In the middle of one of the islands is an obelisk, humming with energy.
It's hypothesized that this obelisk is either the reason for the storms, or the floating islands, or both. Unfortunately, decades of study haven't given anyone the slightest idea how the thing works.
This obelisk has been the driving force behind the development of a multi-island alliance called the Isles United Naval Expedition, or IUNE. IUNE spent several decades constructing the Doherty Outreach Center, which is basically a shipyard attached to giant lift which can transport people to sea-level and back.
After the DOC's completion, IUNE charted multiple ships to go out and explore the seemingly endless ocean of the world beneath. For ten years, these ships explored, while humanity continued dreaming and advancing on the islands. For a while, the explorations were out of the public's mind.
Then one of the expeditions found another obelisk at sea-level.
Suddenly there was a mad rush to explore, and IUNE was thrust to the forefront of society like never before, being urged to send out more ships, and construct more lifts. The answers were out there, and who knew what else.
So, the characters would most likely be a group of people who volunteered for one of these chartered missions. I don't think there would be any real limitations to who could apply, besides the volunteers not being insane.
I'm still trying to decide on the technology level for this RP. Either modern day or somewhat earlier than that. Feel free to ask any questions.