Wani Ocean

The Wani Ocean (海洋の和邇, “Kaiyō no Wani“, Viz: "Crocodile Ocean") is the ocean separating the Shinobi continent from the Temujin continent. It is dotted with islands and is an essential mode of travel for world economies, making up some 25% of all trade in the world. For some odd reason, however, boats come up missing in the ocean periodically when drawing too close to islands. Either that or entire crews may be vacated from a boat only for a "ghost ship" to be seen sailing aimlessly through the blue waters.

Wikipedia Article