When Capt. George Vancouver explored the area in 1794, Glacier Bay didn't exist: the Grand Pacific Glacier filled it almost all the way out to its mouth at Icy Strait. But when John Muir visited in 1879, the ice had retreated 30 miles, leaving behind the steep-sided fjord known as Glacier Bay. By 1916 the ice had retreated the full 60-mile length of the bay, & the massive Grand Pacific ended at the head of Tarr Inlet.
This is the smaller(!) LaPerouse Glacier on the ocean side of Glacier Bay National Park. The bay itself runs inland on the far side of that mountain range. It's hard to get a true sense of the scale here, but those little textury green things are mature spruce trees, & the visible peak is 7588 ft; Mt.. La Perouse beyond rises to 10,728 ft (3270 meters).