Maelstrom
There is an area near the very center of the Central Sea known as the Maelstrom. Sudden storms, whirlpools, kraken sightings, and many other dangers are said to be so common in that area that traversing it is considered suicide to most sailors (the Aether Spira equivalent to the Bermuda Triangle). Some say it is where the sea god dwells and his wrath should not be provoked by approaching it. This is why most all sailing routes go around the edges of the Central Sea and not directly through it.