Hanging Lake is one of the most popular short hikes in the Colorado Rockies. It is not hard to see why, as the lake is a beautiful turquoise with a moss-covered waterfall feeding it. That said, for this reason, it is a very busy trail, and the parking lot is not very large (it fits about 100 cars). Therefore, it is important to get there early, especially on weekends.
To get there, you can drive about 9 miles east on I-70 from Glenwood Springs and get off on the CDOT Hanging Lake rest area. Note that the only way out of the rest area is on I-70 heading east, so if you need to go back west, you will need to drive to the next exit. If you start in Denver, you will need to drive past the rest area, get off on the next exit (at the Grizzly Creek rest area), and head back east. An alternative is to walk or ride a bicycle from Glenwood Springs.
Once you park at the Hanging Lake rest area, walk east about 0.4 miles on the path along the Colorado River. At that point, turn left (north) on the trail, which follows Dead Horse Creek (and later East Fork Dead Horse Creek) to the lake. The hike is only another 1.25 miles from there, but it is very steep and rocky, ascending just over 1,000 feet over that distance. The last stretch actually has stair-like steps and a rail to hold on to. All considered, the roundtrip hike is about 3.25 miles, including almost a mile on the path.
The reward at the top is a beautiful turquoise lake in a small basin that appears to be hanging from the surrounding cliffs. The edges of the lake are made of travertine, built up as limestone particles accumulated over hundreds of years. Those formations are very fragile, and unfortunately there has been damage resulting from the heavy volume of visitors to the lake. Therefore, it is probihited to access the lake or swim on it. There has actually been discussion about limiting access to the area, so it is important to observe all regulations to prevent further damage.
Above the lake is another waterfall, with some of the water coming through a hole in the rock, thus the name Hole in the Rock. In winter, as water drips, ice builds up and makes beautiful formations. If you will visit the site in winter, make sure to wear campons, as several sections of the trail can be slippery.
After the hike, you may enjoy soaking in the hot springs in Glenwood Springs.