The Storval Deep is an enormous freshwater lake found on the Storval Plateau of central Varisia. It spans the entire valley between the Iron Peaks to its west and the Wyvern Mountains to the east, and is fed by three major rivers: the Kazaron, the Storval River, and the Muschkal. It empties through the massive dam known as Skull's Crossing at its southern end into the Skull River.
The lake is a giant-made relic from the time of the Thassilonian empire, a monument to the vanity of Runelord Karzoug. This part of Varisia once supplied most of the stone for the countless Thassilonian cities and monuments of the ancient empire. When it finally was played out, Karzoug decreed that the Skull River should be dammed, and its waters cover the ugliest scar in his domain. To this day, evidence of ancient quarrying can still be seen in many places along the shores of the lake, prompting much speculation amongst locals, as the true history of the Deep is known to very few. The most notorious inhabitant of the Storval Deep is a creature known as Black Magga, a hideous monstrosity so old, she is rumored to pre-date even the gods.
- James L. Sutter. (2007). Varisia. The Hook Mountain Massacre, p. 62. Paizo Publishing, LLC. ISBN 978-1-60125-038-4
- Adam Daigle and James L. Sutter. (2012). Rise of the Runelords Anniversary Edition Player's Guide, p. 13. Paizo Publishing, LLC.
- Nicolas Logue. (2007). The Hook Mountain Massacre. The Hook Mountain Massacre, p. 40. Paizo Publishing, LLC. ISBN 978-1-60125-038-4
- James L. Sutter. (2007). Varisia. The Hook Mountain Massacre, p. 68. Paizo Publishing, LLC. ISBN 978-1-60125-038-4
- Nicolas Logue. (2007). Bestiary. The Hook Mountain Massacre, p. 89. Paizo Publishing, LLC. ISBN 978-1-60125-038-4