In contrast to the great Sea of Dreams farther to the south and west, the Dreamless Sea is a landlocked body of water within the continent of Addar, filling much of the shallow, closed basin between the Shadow Mountains and the Jarlschlager Range. The sea is fed by several rivers and streams, the largest being the Arcos River which drains the sprawling Arcosian Swamp, but it has no natural outflow and is highly saline.

Salt flats line the lake's low northeastern coast, while at the southwestern end stand the great Gull's Eye Cliffs within the Duchy of Elebron. Most of the rest of the sea is enclosed by the Kingdom of Evenhold, save for a 15-mile stretch in the extreme northeast controlled by Sicilia.

Few fish live in the sea's salty waters, but brine shrimp, salt flies, and millions of migratory birds thrive there. Enormous mud-lobber wasps also buzz around parts of the shoreline, gathering mud for their nests and pelting unwary passers-by. One of the few islands in the sea is Castanamir's Island, named for a powerful mage who made it his home, but in 998 YA it inexplicably disappeared without a trace.