Start at the right trailhead
We initially thought these trails started directly at Many Glacier Hotel. They do not. The Iceberg-Ptarmigan Trailhead is behind the Swiftcurrent Motor Inn area. Starting from the hotel adds extra walking before you even begin the hike.
The shared trail
The routes share their opening miles before splitting. NPS lists Ptarmigan Falls at 2.7 miles from the trailhead. From there, the Ptarmigan route keeps climbing toward Ptarmigan Lake and the tunnel, while the Iceberg route heads toward Iceberg Lake.
Ptarmigan Tunnel
The climb above Ptarmigan Lake looks more intimidating from below than it feels once you are on the switchbacks. Take it slowly. The tunnel itself is one of the most unusual features we encountered in Glacier, a 183-foot passage cut through the mountain for hikers and horseback riders.
Coming out the other side completely changes the view. You look into the Belly River country, with Elizabeth Lake visible below on a clear day. The rock around the tunnel is striking too, with layered colors and textures that make the pass feel very different from the lake trails below.
The tunnel doors generally open from mid-July into late September, depending on conditions, so check trail status before planning around it.
Iceberg Lake
After returning to the junction, we continued to Iceberg Lake. NPS lists the lake at 4.8 miles one way from the trailhead. The final basin is spectacular, with cold turquoise water tucked below huge cliffs.
Put your feet in if you want to understand how cold it is. We did, briefly.
The wildlife moment
Near the lake area we saw a huge bull moose, one of the best wildlife sightings of the trip. That is also a reminder that this is wildlife habitat, not just a hiking corridor. Carry bear spray and give every animal a lot of space.
If you only have time for one Many Glacier hike
We would still choose Grinnell Glacier. But if you have another full day, Ptarmigan Tunnel and Iceberg Lake are both exceptional, and stacking them makes sense for strong hikers because of the shared approach.