A number of people have asked us about hiking off trail, so we thought we'd add a few notes here.
First of all: hiking off trail is only for people who know how to use a map and compass. You have to know where you are, and where you are trying to get. And you have to know what kind of terrain lies between those two points. That's where a GPS will let you down. You can be at the top of Half Dome and only be half a mile from Mirror Lake...but that half mile is straight down, and you can't get there. A topo map will show you if it's possible. And it will also show you some other ways to get around the obstacles you might find.
Which brings us to: You can't always get there. We took a hike last year that included trying to go directly from Yellowhammer Lake to Leighton Lake in the Emigrant Wilderness. We spent about two hours trying to find a route that didn't include climbing straight up a cliff...and never did find one. We turned around, spent the night at lovely Five-acre Lake, at left, and studied the maps and terrain some more. The next morning we found a much easier and longer route that went around the cliff, and happily hiked out.
But it's important to have a good idea of what you can do, what you can do with a pack on, and what your partner is comfortable doing. Don't mess with those.
Third of all: Cross-country miles are different. Hiking without a trail not only involves route finding and map reading--it is also a question of where you put just about every foot on every step. That takes longer than hiking on a trail. So we figure that if we are going off trail, it will take use about twice as long to cover the same mileage. On our last trip out of Tuolumne Meadows in Yosemite, we left Nelson Lake to go cross country to Reymann Lake and then over the saddle to Tuolumne Pass.
That's a total of something like three miles as the crow flies, and it took us three hours. Not exactly record speed. Once we hit the trail, our speed picked up to our usual two miles per hour or so (unless we are climbing steeply!) If you DO go off trail, make sure you give yourself enough time to enjoy the journey--and complete it! The Sierra is ideally suited for hiking off trail---the forests are generally open, the granite can often provide a nice sidewalk for your path, and you can often find slopes that are perfectly manageable even with a backpack.
On the other hand....You can also find Manzanita and alders that are an impenetrable thicket, and take hours to bushwhack through. Not fun. Or a meadow that looks easy to cross, until you find it a marshy bog that sucks your legs up to the thighs. And those huge blocks of granite are no fun on a talus slope where you have to clamber and pick your way from on top of one refrigerator to another. And those gentle slopes of granite can slowly increase to steep and slippery ramps that make a single mistake a painful, if not fatal, accident.
Be careful out there.