Stretching from the northernmost part of Concordia's Great Coastal Expanse to the northern tip of Tricornucopia, the Emerald Sea is a vast expanse of oceanic vegetation, the most massive kelp forest in the world. Many of these sea plants grow to immense heights, some sending stalks and leaves twenty or thirty feet above the surface of the water, and groves of such plants can give a convincing illusion of land.

A variety of creatures are adapted to this underwater jungle, either swimming between the vegetation or, like the sea lemur, actually clambering and climbing among them. Many birds actually nest out on the water, and one species, the sea hummingbird, almost never comes to actual land.

The Emerald Sea is also home to many sapients, ranging from the tiny Ebbies to the massive Grey Whales who occasionally visit, but the most prominent citizens of the country are the Merrow.

Originally native to Glascolt/Coltland, the Merrow, or sea changelings, are less adept shape-shifters than their land-dwelling cousins, and cannot truly fly, though their wings give them a gliding distance of up to a mile.

A sizable population dwells in the Emerald Sea, and they have made three cities for themselves. Samguba is the capitol, from which Queen Pistol rules her people. Murdúchand is a fortress, heavily fortified and well-protected, a place where citizens can seek refuge if the country is under severe danger. Finally, Kelptrade Town is an amphibious port town, where canals and bridges take the place of roads, allowing land and sea races to freely hawk their wares with one another.

West of the kelp forests is an expansive underwater prairie of seagrass, mostly home to roaming Manatee nomads. Beyond this, before a massive drop-off, is a red algal reef, dominated by red algae instead of coral, and home to a variety of fully aquatic turtles adapted to this environment, Additionally, this is the home of two species of marine amphibian, as well as a frogfish relative which feasts on them.

Protecting Murdúchand to the west are a series of razor-sharp rocks, hidden below the water's surface, and hard enough to sink any boat which dares attempt to cross them.

In the south (and in the Merrow's opinion protecting the Emerald Sea from Tricornucopia) is a deep abyssal rift known as the Gash. It has never been explored, and no one sails or swims over it. All light seems to vanish below its opening, and even krakens which accidentally stray from deeper waters avoid it.

It should not be surprising that the Emerald Sea's main export is a variety of edible sea plants