Avalon Bay is the northernmost extension of Lake Encarthan. It borders Ustalav to the west and north, and Razmiran to the east. Major settlements on the bay include the Ustalavic capital Caliphas, in addition to the settlements of Vauntil, Thrushmoor, and Illmarsh.
Shalako and the gillmen of the House of the Rising Tide discovered a triton city beneath Avalon Bay but found it barricaded by a skum army. Their attempts to learn more about said army led to the discovery of a magical barrier protecting the skum. Orin turned to the Frozen Heart of Orphys to learn more about the barrier.