As you enter Glacier Bay in Southeast Alaska you will cruise along shorelines completely covered by ice just 200 years ago.

Explorer Captain George Vancouver found Icy Strait choked with ice in 1794, and Glacier Bay was barely an indented glacier. That glacier was more than 4000 ft. thick, up to 20 miles or more wide, and extended more than 100 miles to the St.Elias Range of mountains.

By 1879 naturist John Muir found that the ice had retreated 48 miles up the bay. By 1916 the Grand Pacific Glacier headed Tarr inlet 65 miles from Glacier Bay's mouth. Such rapid retreat is known nowhere else on earth! Scientists have documented it, hoping to learn how glacial activity relates to climate changes.
Glacier Bay National Park includes 16 tidewater glaciers:12 actively calve icebergs into the bay. The show can be spectacular. As water undermines the ice fronts, great blocks of ice up to 200 feet high break loose and crash into the water.

The Johns Hopkins Glacier calves such volumes of ice that it is seldom possible to approach its ice cliffs closer than about 2 miles.

The glaciers seen here today are remnants of a general ice advance- the Little Ice Age- that began about 4,000 years ago. This advance in no way approached the extent of continental glaciation during Pleistocene time.