The courses of the rivers Parrett, Somerset Axe, Brue and Cary run across the Somerset Levels and have generally been changed to improve the flow. The River Axe rises from Wookey Hole Caves, due to water draining into the ground at swallet holes on top of the Mendips. The river passes through Panborough Moor, Wedmore Moor, Ox Moor, Stoke Moor and Mark Moor and reaches the sea at Uphill (near Weston-super-Mare) on Bridgwater Bay.