Glacier National Park: Grinnell and Highline Loop Link Professional Review and Guide
"Explore the most rugged, scenic, and wildlife-rich mountains in the Lower 48 on an epic day hike.
On this 14.2-mile hike, you'll climb past lakes, waterfalls, and the park's biggest glacier on the Garden Wall, then you'll descend through the best wildlife habitat in the Glacier. You'll need an ice ax, helmet, and possibly crampons, since you connect the Grinnell Glacier and Highline Trails via a snow gully.
The best time is June, when snow fills the gully. Going this direction lets you see cornice conditions before committing."