Andrews Glacier is probably the 2nd easiest route to get to the Continental Divide from the east side of Rocky Mountain National Park, the easiest being the nearby Flattop Mountain trail. (If you think that driving your car to Milner Pass is even easier, then you are surfing the wrong web site!)
The glacier was named for Edwin B. Andrews, a relative of Abner Sprague. These two men climbed to the glacier in 1897, and Sprague named it for Andrews since he was one of the area's best fishermen. Sprague settled in the Park in 1875, was an early landowner, hotel owner, guide, and Estes Park historian. Several features in the Park are named for him. (Source: High Country Names by Louisa Arps and Elinor Kingery)
Andrews is a year round glacial snowfield that is perfect for beginning practice with ice axe and crampons. It is generally between 20 and 25 degrees in slope, so safe from avalanche danger and perfect for practice work. Actually, ski poles, snow shoes, or good waterproof hiking boots might be all you need on many days. However, there are conditions when decent crampons are necessary. A friend of mine had only small instep crampons on a bright October day, and they were not sufficient to ascend the hard ice.
Conditions can range from perfect, firm snow in summer or winter, to post holing slush in spring, or solid glacial ice in fall. Sometimes several of these conditions exist together, so you can choose a line that suits what you are looking for.
Andrews is the usual descent route for the more difficult climbs from Sky Pond, such as Taylor Glacier or the north face of Mount Powell. It also provides an excellent alternative descent from climbs of Flattop Mountain, Tyndall Glacier, or Chaotic Glacier. This makes for a spectacular circular route that can take in up to five Continental Divide summits. If you chose to descend Andrews note that it dumps into an icy cold tarn. Although I personally don't know anyone who has slid into this lovely pool, I'm sure it has happened. Best to remain in control while glissading!
I have seen some exposed crevasses on Andrews in the fall, at different locations in different years. One extended nearly across the entire center of the Glacier, about 10 feet deep. It required climbing down into it, then some of steep front-pointing steps to get onto the uphill slopes. Another was a large cavernous opening near the upper south side of the glacier. It could have swallowed several elephants without a trace.
See the Getting There section on the main page for directions to the Glacier Gorge trailhead. Note that the new trailhead parking lot is slightly larger than the old one, but will still fill up early. However, since you are climbing something you will be there before it is full. :-)
The standard trails takes you to Alberta Falls, then continues on another 2 miles to a major trail junction that splits towards Black Lake (left), Lake Haiyaha (right) and Loch Vale (center). At this junction take the Loch Vale fork.
Climber's trail shortcut: Most climbers use an unmarked trail to reach this fork. It cuts 15-20 minutes off the hike and bypasses Alberta Falls and the switchbacks above it. The trail begins immediately after the fourth bridge, slightly more than 0.3 miles from the new trailhead. (The third bridge is a small, single log affair, I am counting that.) After crossing the fourth bridge, turn right and make your way up the slope. The path is faint at first but soon develops into a full-fledged, well-maintained trail. It joins up with the main trail 100 feet below the junction. This is also the standard winter route.
In winter, the route from this junction usually turns towards Black Lake for about 100 yards, then turns right and follows the stream drainage up to Loch Vale Lake.
At Loch Vale Lake you can see Andrews Glacier by looking toward your right up the narrow gorge call The Gash. Taylor Peak is mostly hidden behind the Sharkstooth ridge, but you will have an excellent view of Taylor Glacier. To the left of this is Mount Powell, and immediately on your left is the steep and huge north face of Thatchtop Mountain.
Continue hiking past Loch Vale to another trail junction that turns right toward Andrews Glacier, taking you into The Gash. There is a marked sign here, which in winter can be buried by snow, or just generally easy to miss if you are breaking trail. But the way into the Gash is about the only place where the path climbs gently to your right after leaving the Loch, and before you arrive at the Cathedral Wall, which is now towering in spectacular fashion above you.
Climb steadily into The Gash. The views of the towering rock pinnacles on both sides of The Gash are impressive, with The Sharkstooth, to your left, being the most prominent feature. After a steep climb near the west end of The Gash you are at the base of Andrews Glacier. It is about 4 miles and 2,200 feet elevation gain from the trailhead.
As noted above, conditions determine what you will need. This can range from just decent hiking boots, to snowshoes, to a mountaineering ice axe and crampons.
"There is no such thing as bad weather, only inappropriate clothing."
--Sir Rannulph Fiennes