The most accessible glaciers are the Blackfeet and the Sperry, both of
which are on the trail leading from St. Mary Lake to Lake McDonald.
Blackfeet Glacier is 2 miles by trail from Gunsight Lake. This is the
largest glacier in the Park, having an area of 3 square miles. The
glacier is especially dangerous in the vicinity of the upper cascades.
Visitors are not allowed to go upon it unless accompanied by
competent guides, who should be supplied with ropes, belts, creepers,
alpenstocks, and emergency equipment. Each visitor to the glacier
should have an alpenstock or stout stick 6 or 7 feet long. The
alpenstock should be used to sound for blind crevasses, and in case a
person breaks through the ice the alpenstock should be thrown across
the crevasse in order to prevent a fall to the bottom.
Sperry Glacier is 2 miles by trail from Sperry Chalets. While the
trail is steep, horses may be used to the foot of the escarpment under
the south rim of the glacier; walking is recommended. The escarpment
may be climbed by means of an iron ladder bolted to the rock, or by
way of zigzag goat trails. Whichever method of ascent is attempted,
visitors should be accompanied by competent guides provided with
ropes. While this glacier is less broken than Blackfeet Glacier,
explorations should not be attempted without a guide.