What's a castle without a lake? Dimwit Flathead loved lakes, but hated to go outside, so he had one constructed in his extensive cellars. Lake Flathead is a large and handsome lake that lies underground, entirely within the caverns near the former location of the royal castle at Flatheadia (before the 883 GUE destruction of Flatheadia it lay entirely within the lower levels of the royal castle).

To the west of the lake lay the Royal Zoo; to the south was the Great Underground Desert, to the north was the Frobozz Philharmonic Orchestra Hall (which was the basement of the FrobozzCo International World Headquarters building); to the east was the Great Underground Mountain; and to the southeast was both the Great Underground Woods and Savannah.

The lake could be crossed via a magnificent royal yacht that never left that lake, docking at four points along the narrow shore. The entire lake was lit from the roof high overhead, which was the floor of the castle itself. A wide stream at the southwest end fed its waters. Once a lovely lake, teeming with life, by the fall of the Empire the waters had grown stagnant. The water was so scummy and murky that a parched camel would not dare to drink from it (although near the floor the water is somewheat clearer). Swimming in the lake is not advised, as the waters are known for their hungry denizens, including the Loch Flatheadia Monster and giant squids.

SOURCE(S): Zork Zero