Jump Isle is the fifth major isle to be discovered off the coast of First Land, and the only one on that land's west coast. Its coastline is roughly 1050 miles around. There is a range of hills extending from nearly the north coast to nearly the south coast, and from the east coast halfway to the west. At the center of the island is a geological feature called Lymon Mists, which was discovered in LY 384, but not widely known until 806.
Jump Isle was discovered in LY 370, by explorers from Ship. While sailing around its coast, the explorers found that not far off was another landmass (which eventually came to be called Near Land), which appeared to be far larger than an isle. It was decided that before that land would be explored, a village should be settled on the recently discovered isle, to serve as a jumping off point for any exploratory expeditions. For this reason, the isle was named "Jump Isle," and the village which would be settled on its northern coast two years later, in 372, would be named Jump Village. However, prior to founding Jump Village, it was decided that a port should be founded nearby on First Land, to serve as a staging point for the settling of Jump Village. That port was called Shipsister.
In 915, a second village, called Moderation, was founded on the southern coast of Jump Isle.