There are a few great hikes that go to Lake Ingalls. The 31 mile out and back, Ingalls Creek trail is one of the most strenuous, longest ( and loneliest ) in the whole Alpine Lake Wilderness. Few hikers complete the entire trail.
Lake Ann- Ingalls Peak loop is shorter ( 19 miles).
But even more hikers ( including me ) plan a short ( 10.8 miles round trip) and easy day hike straight to Lake Ingalls.
I hear that Lake Ingalls is a popular destination and draws crowds of people in summer time. Though, parking lot was full, we didn't meet too many people along the way or even by the lake.
A couple cool features of the trail :
Ingalls Pass is dotted with many great camping spots ( official with toilets and ...."less official" ).
Mountain goats roam around the lake as if they owe the place ( one particular goat struck a pose and practically told me : " It's time for you to go").
Ingalls Lake is beautiful, inviting and...freezingly cold. Yet, a few "brave" hikers reward themselves with a cool dip ( or a cold plunge ) in the lake.
If you happen to have "hiking fishing gear" among your "10 essentials" ( fish hooks, line and some artificial lures ), try your luck fishing for trout. Want to have more "fish fun" ? Try "trout tickling" :)
One piece of gear I would recommend - insect repellent.
For a guide book, check out Backpacking Washington's Alpine Lakes Wilderness