River Flux
From Tardis Wiki, the free Doctor Who reference
The Flux was a river in Elbyon on Avalon which fed into the Circle Sea. The city of Fluxford was located on the river, with the town of Fluxmouth located at the river's estuary at the sea. In 2991, the First Doctor and Ian Chesterton travelled aboard the Merrow to the Circle Sea and eventually to Helm Island. (PROSE The Sorcerer's Apprentice)