Portal Key

The Portal Key is an enchanted key that allows one to use the portals to travel between the two levels of Irenicus' Dungeon in Baldur's Gate II: Shadows of Amn.

Location

 * In the chest at the foot of the bed in the replica of Ellesime's quarters at the end of the Dryad Grotto.

In-game description
"An intricate key, presumably once owned by the lover of your captor."