Bathmulg is surrounded by a belt of hills and mountains. The valley has little vegetation. After heavy rainfalls, vast lakes form on the surface of this orange clay flatland. The water is never more than several inches deep, and it remains for several days until seeping into the clay. The hotter months see Bathmulg turn into a cracked field.
Many bugbear tribes in the surrounding hills and mountains use the area's clay to build crude huts. For a time in the Second Epoch, under a green dragon named Mathongrarg, they lived more respectfully. They lived in a great labyrinth beneath the surface, serving as the outer defense for the passages leading into this dragon's lair. The dragon's long slumbers, her minions unattended for years on end, ended with the bugbears moving on to better living conditions. A few weeks later, a drow war party caught Mathongrarg in her sleep, killing her on 28 Saunas 1201.
Bathmulg's most remarkable feature is a cavity called Mathongrargs Eye. At night, the green glow from this huge hole radiates outward for miles around. Its source is a marvel called the Ink Sphere.