A glacier with ice caves

Originally known as Sitaantaagu ("the Glacier Behind the Town") or Aak'wtaaksit ("the Glacier Behind the Little Lake") is about 19 km long glacier with fascinating ice caves inside it. Together with the surrounding landscape is part of a protected area, a federally designated unit of the Tongass National Forest.

The glacier's retreat
Because of the climate changes, the glacier has retreated 2.82 km since 1958, and over 4.0 km since 1500. It is possible that the glacier might experience a period of stabilization during its retreating march, because increasing amounts of warm air will be carried up to the head of the icefield, where colder ambient temperatures will cause it to precipitate as snow. The now will then feed the icefield. However, this interesting phenomenon will fade away if temperatures continue to climb.

Ice caves
There are several ice caves inside the glacier, that are quite challenging to access. People usually take one of the two general routes to get there: over land and over the lake. Both routes involve hazards not normally found on trails and it is strongly recommended to go with someone who knows the route.

The blue ice
The ice in the caves appears blue. That is because it absorbs all colors of the visible light spectrum except blue, which it transmits. Glacier ice may also appear white because some ice is highly fractured with air pockets and indiscriminately scatters the visible light spectrum.

Visitor Center
The United States Forest Service operates the area as part of the Tongass National Forest, offering interpretive programs throughout the year for children and adults with stunning views of a lake-terminating, calving glacier. It was the first U.S. Forest Service visitor center built in the nation. Today, the exhibits in the Center cover the history of the glacier and depict the variety of wildlife in the area including mountain goats, wolves, black bears and salmon in the nearby streams.

Source 2: http://www.fs.usda.gov/detail/tongass/about-forest/offices/?cid=stelprdb5401454
Image Source: http://greatadventure24.com/visit-alaska-travel-destinations/