The island of Sedna are a naturally inhospitable place to outsiders. Located in the a patch of the [Eastern Ocean Name] known for powerful storms and unpredictable rocky outcroppings, the island itself is formed by a ring of formidable sheer cliffs that offer little opportunity for safe passage into the interior of the island. Most sailors find the dangerous island not worth the trouble with so many easier pickings just north, and because of this, Sedna has remained mostly cut off from the world at large. The locals prefer it this way and actively discourage all but a chosen few ships who dare to come their way.
Due to the harsh life on the island, the Sedna people put a heavy emphasis on utility. Everyone is expected to be useful and industrious, and when you cease to be, your status in the colony falls dramatically. Because of this, the small amount of people have managed to make a significant imprint on the island. The Sednans carve their villages into the very sides of the cliffs. Tunnels, removable rope bridges, and ladders are the common form of travel between sections of the island. The bridges and ladders removable to make it nearly impossible for outsiders and local dangerous fauna to reach them.
Twice a year, the Sedna people invite two ships in to trade for various goods they could not produce on the island, in exchange for raw opals, coral, and crafted jewelry. They are careful to not appear too friendly or wealthy, so as not to encourage the sailors to get any sly ideas. Once a crew made the mistake of reneging on their deal and the hail of death came from the cliffs above them. The people partially sunk the ship just outside of the island entrance as a warning where it remains to this day.
In the absence of outside knowledge, strange customs have cropped up on Sedna. The usual pantheon of gods are barely a presence, replaced with the idea of Animism: in which everything has its own individual spirit. With the natural unpredictability of living on an island, they attribute misfortune to angry spirits and do everything in their power to keep them happy. The most important being the spirit of the island itself.
The heart of the the Spirit Sedna, is located on the largest portion of the island, inside a seemingly endless system of underwater caverns, filled by a spring with fresh water. Once every season, the colony chooses the Strongest to take an offering of food and goods into the caverns. They are given a 36 hours to swim as deep as possible into the caverns and leave the offering as close the the spirit’s heart as possible. More than once, the Strongest has drowned in the process, after which the island is often hit by sudden storms.