A small alpine tarn in a hanging valley at 2,135 m (7,005 ft), accessible via a steep trail (3.4–3.8 km, 385–495 m gain) from the Chateau Lake Louise lakeshore. Lake Agnes sits in a cirque beneath the Big Beehive and Little Beehive and is home to the historic Lake Agnes Tea House, built by the CPR in 1901. The lake drains toward Mirror Lake below via a dramatic waterfall; steep wooden stairs lead past the falls to the tea house.

Geology. The Beehives bracket a hanging valley; a secondary glacial valley carved by a smaller glacier that could not erode as deeply as the main Lake Louise trunk glacier. As the Victoria Glacier retreated, it left behind the basin for Lake Agnes. Glacial rock flour from active erosion gives Lake Louise and Lake Agnes their turquoise colour, peaking in summer melt season.

Namesake. Likely named for Lady Susan Agnes MacDonald (née Bernard), wife of Sir John A. Macdonald. Her 1886 CPR journey; including riding the cowcatcher for views; and her book By Car and by Cowcatcher helped popularize the Rockies. A secondary namesake, Agnes Knox (Toronto, 1890), is also cited.

Ecology. The corridor spans montane to alpine zones. Mount Niblock (2,976 m) and Mount Whyte (2,983 m) rise above Lake Agnes to the northwest. Alpine Larch (Larix lyallii) turns golden in mid-to-late September (“larch season”); a two-week peak that drives visitation. Meadows host Glacier Lily, Indian Paintbrush, and Western Anemone. Grizzly bears forage on glacier lily bulbs in spring and berries in fall; the area is part of the Whitehorn Wildlife Corridor. Bear-aware behaviour required. See the Lake Agnes Trail for a full hiking guide, the Lake Louise Tea House System for planning, and the summer trail page for stats.