Goat, the oddly-named underwater country, was a massive body of water in ancient times that allowed you to raise your monsters underwater. The waters of Goat were said to be extremely high in oxygen (possibly a side-effect of the world's largest oyster living there), explaining why and how land monsters were said to have no trouble living under the sea. Goat is one of the training locations in Monster Rancher 3.
It is said that there was a race of people who lived most of their lives underwater in Goat, ruled by a queen named Ogyo. These people built a large Octopee statue in the center of the estuary, and perhaps many of the Sunken Temples found on Pangaea today.
Since Goat no longer exists as a country (probably filled in when the Western Continent was formed), it is now the name of the ocean between the Eastern and Western Continents, and the waters surrounding Antalya are known as Goat Bay.
Its MR3 boss is the SeaLord.