This is Schrawynghop, the Marsh of Daemons, Oare Marshes in modern English, on Swale Creek off the Medway. Nearby are the Shining Cliffs, the white chalk cliffs of Kent. In the Anglo-Saxon story Beowulf, the oldest in the English language, the monster Grendal lived here.
The Kent marshes are largely drained now but the heavy rain this year has saturated the soil, returning this last remnant to something resembling its original state.
Looking out on the Isle of Harty from the site of Harty Ferry. Harty is now part of the Isle of Sheppy. This is the probable site of Heorot in the poem. In the Dark Ages Harty would have been a hill in a marsh open to the sea to the east at Warden Point. The Swale has been heavily canalised like most English waterways.