Olodel was an island in the north-west Lake of Steam. It and its "sister" island, Narruth, were very different.
Olodel was once a private hunting preserve for wealthy Calishite merchants. They brought in deepspawn to disgorge countless monsters for them to hunt. The island eventually was overrun by beholders and other monsters.
The heart of the island contained a tunnel system that led directly to the Underdark beholder city of Zokir.