St. Mary's Glacier

Short but steep hike to a picture-perfect alpine lake and small glacier, with the option to hike on its year-round snow.

Hiking Difficult

3.3 km
252 m
252 m
1-2 hrs
Low Point
3.2 km
High Point
3.4 km
St. Mary's Glacier Map

St. Mary’s Glacier and the lake beneath it are a fantastic introduction to the alpine realm of the Rocky Mountains. This is a true alpine lake, formed by a mass of ice called a glacier that carved away at the mountainside. The glacier still exists but is today much smaller than it once was. This is St. Mary’s Glacier, and you can hike on it after reaching the lake and continuing uphill.


The hike begins from the community of Alice near Idaho Springs, just over an hour’s drive from Denver. Park in one of two lots, pay the $5 fee, then walk along the road to access the trailhead. The trail is wide and easy to follow, but steep and rocky. You’ll be trudging up loose stones for much of the way, so be sure to wear good shoes. The trail reaches the lake in only about 3/4 of a mile.

People come here all year, but most come in the summer. Winter and spring require skis or snowshoes. The lake stays frozen until May, and though the water stays frigid all summer, the air is warm enough that dipping your feet or even taking a swim can be enjoyable. Whether or not you choose to get wet, the lake is a comfortable place to relax and take in the view. The shore is made of gravel and larger rocks that are good for sitting and lounging. Open areas give room to spread out, even if there are lots of people around.

On one side of the lake are a bunch of old, gnarled pine trees, with denser conifer forest beyond. On the other side, vertical cliffs meet the water and the mountain towers above. In the notch between two peaks lies the glacier, a streak of permanent ice and snow. Most of it melts by late summer, but earlier in the season it’s an impressive snowfield. You may even see people skiing it in mid-summer.

To reach the glacier, just keep hiking. Beyond the lake, a dirt path weaves through some greenery then emerges on the rocky, barren slope beneath the glacier. Depending on conditions, you may be hiking in snow by this point already. If not, continue uphill to reach it. The snowfield is quite steep, and traction devices on your shoes are required to climb it safely, but you may be able to walk around on the rocks. This part of the hike may be easy or hard, depending on the amount of snow, firmness of the snow, wetness of the rocks, and a lot of other factors. Use your best judgment and play it safe.

Be prepared for varying terrain and changing weather, even if you go no farther than the lake. Thunderstorms often pop up on summer afternoons, so don’t hesitate to return downhill if the weather looks bad.




Hiking trails where obstacles such as rocks or roots are prevalent. Some obstacles can require care to step over or around. At times, the trail can be worn and eroded. The grade of the trail is generally quite steep, and can often lead to strenuous hiking.

Medium Exposure

2 out of 4

The trail contains some obstacles such as outcroppings and rock which could cause injury.


1 out of 4

Close to help in case of emergency.

Best time to visit

May, June, July, August, September, October


  • Alpine
  • Wildlife
  • Picturesque
  • Dog friendly
  • Wild flowers
  • Water features
  • Family friendly

Guidebooks in this area