Shallows

Shallows are areas of shallow water that can be traversed without need of a water vessel. They are often denoted on the world map by areas where the water is dotted with stones.

Final Fantasy IV
In Final Fantasy IV, various areas of water between landmasses have shallow water that can be traveled over while in the Hovercraft.

Final Fantasy VII
Shallow water exists in Final Fantasy VII where, like rivers, a Blue, Black, or Gold Chocobo is required to cross them.