Fihrgrell is an ocean of the Abyss world Kurun'Ush.
In the Demon Spawn War, a rift was opened at the head of Bal-Kriav's Moredhel Valley. This created a link between this valley and an ocean of another world. At of the Moredhel-Fihrgrell Rift (9266 GE), seawater flooded the valley. It created lake Moharr, then continued west, draining into the Ratanur Trap. It was named thus because of a null mine used to create a counter rift, one that fittingly came to be known as the Fihrgrell Drain (9274 GE).
In 9457 GE, Thyrm, serving under the Quarat'un Covenant, stoppered the Moredhel-Fihrgrell Rift with The Frozen Titan, the area around it became the unnatural glacier Fihrgrell Cap. With a dam in place, the flow from one side of the rift to another was reduced to the natural melting of the glacier around.