The Guivre wetlands is the result of the joining of three rivers, the Famirótan, the Irudrarg, and the Cenyemo. When any of these rivers overflow, as they often do, it adds to the huge numbers of ponds and mires that dot the area. In the northern parts where the waters of this area drain into the Core Sea, there are hundreds of geysers and steaming pools. This geothermal activity is the result of a wide lava river flowing hundreds of feet underneath.

Ships and other craft, Orchish Empire commerce, cut through the swamp by way of the Irudrarg. They have their the ports on the Core Sea and the uplands lake Virgath. Commerce also makes it way west by way of the Famirótan. From this east to west river, the trade is normally between the elven states Lúinwë and Ithengee.