The Pacific Crest Trail runs for 2,500 miles, generally following mountain divides, from Mexico to Canada. I am only going to show a very small part of this trail, going east from the old interstate 40 near Donner Summit toward the current interstate (I-80). If you go up the old highway from Donner Lake, go past the arched bridge and continue up the hill. The trailhead is directly across the road from the Sugar Bowl training center.
The main trail is a nice hike in itself - not terribly strenuous but with a fair amount of ups and downs and some great views of the granite cliffs and Donner Lake. Last year I discovered that if you take some of the side trails, it is even better. It is these side trails that I will be describing since people are less likely to find them on their own.
The first side trail is off to the right shortly after trail begins. It takes you a very short distance to a nice view of Donner Lake from large granite boulders. Then continue on main trail.
When you pass under some power lines, look for trail off to your left. This trail is not very clear in places. You are climbing over rock so it is easy to lose it. Look for the tree that has 2 trunks shaped in V (see photo). Path goes to the left of this tree. Continue till you reach the dead tree (photo) and then turn right up the hill. There is not a clear path here so just head up the hill and wander a little to find a little pond in a granite basin (several photos here because I loved this little pool). A bit of a surprise as it has a lot of miniature catfish in it.
The story I heard from another hiker was that the pool had originally been stocked by Chinese coolies who were building the railroad back in the 1800s. Over time, the catfish had acclimatized to the small pool by becoming smaller, even when full grown. I don't know if the story is true but they are very small catfish in an unexpected place.
If you continue in the same general direction (west), you will see a trail. Follow it for a short distance and you will come to Angela Lake (photo). Turn right and follow the shore a ways until you see another path going off to your right (it is before you get to the end of the lake). Take this trail to return to the main Pacific Crest trail and continue east. The trail zig zags back and forth up the hill. Shortly past that, you will see another trail off to your right. If you take that, it leads to another great view of Donner Lake. Part of this trail is also difficult to see as it crosses granite so there is no trail. Just wander a little and you will find it. You won't be going far and can't get lost.