Of Yosemite's three sequoia groves—the others being Merced and Tuolumne, both near Crane Flat well to the north—Mariposa is by far the largest and easiest to walk around. Grizzly Giant, whose base measures 96 feet around, has been estimated to be one of the largest in the world. Perhaps more astoundingly, it's about 1,800 years old. Up the hill, you'll find more sequoias, a small museum, and fewer people. Summer weekends are usually crowded here.
Please note that due to major reconstruction the lower grove, which includes Grizzly Giant, Fallen Monarch, and the California Tunnel Tree, will be closed through November 2016. The upper grove may be open intermittently during this time. Shuttle service from Wawona will not be available in 2016. Check the Yosemite website before visiting this area in 2016 or 2017.
Rte. 41, 2 miles north of the South Entrance station, Yosemite National Park, California, 95389, United States