From Obertraun you can catch a cable car to Krippenstein (2109m), where you'll find the 5 Fingers viewing platform, which protrudes over a sheer cliff face in five differently shaped platforms (one is reminiscent of a diving board). On a clear day the views from here down across the lake are little short of magnificent; a glass floor allows you to peer directly down beyond your feet into a gaping void. It will either cure your vertigo or turn you into a blathering mess.