This picture was taken from the Porcupine USFS campground at the end of the Hope Highway an the south side of Turnagain Arm. That is, about 20 miles south of Anchorage and across the bay, but a long drive around to get there. There is a large rise and fall of tide surge here. This picture is at low tide with the bottom of the bay exposed. At high tide there's about 20 feet of water all the way across the bay. The Seward Highway runs along the north side of Turnagain arm, just in front of the mountains in the background.