Calaveras Big Trees State Park Discovery Tree shown above the stump of one of the first trees that was used to prove that this incredible grove exists. For over 150 years the tree stump and remainder of the tree have laid on the ground. One portion served as a bowling alley and bar. One of California State Parks most interesting parks to wander through, especially in the fall, you really must visit this park at least once during your California travels.

Sierra redwood trees are the largest trees in the world. Many sierra redwoods are between 250 and 300 feet tall, the tallest being about 325 feet high. While their height is impressive, the real wonder of a sierra redwood lies in its bulk. Many of these giants have diameters in excess of 30 feet near the ground, with a corresponding circumference of over 94 feet!

The largest redwood in Calaveras Big Trees State Park is the Louis Agassiz tree. It is located in the South Grove. This tree is "only" 250 feet tall, but it is over 25 feet in diameter six feet above the ground! The largest tree in the North Grove is probably the Empire State Tree, which is 18 feet in diameter six feet above the ground. The largest tree in the world is the General Grant tree, located in Sequoia-Kings Canyon National Park It stands 271 feet tall and is 28 feet in diameter at six feet above the ground.

Calaveras Big Trees State Park, located 4 miles (6 km) northeast of Arnold, California in the middle altitudes of the Sierra Nevada in Calaveras County, became a state park in 1931 to preserve the North Calaveras Grove of Giant Sequoias. It has been a major tourist attraction since 1852, when the existence of the trees was first widely reported, and is considered the longest continuously operated tourist facility in California.

Over the years, other parcels of mixed conifer forests, including the much larger South Calaveras Grove of Giant Sequoias (purchased in 1954 for $2.8 million USD), have been added to the park to bring the total area to about 26 km² (6,500 acres). The North Grove contains about 100 mature giant sequoias; the South Grove, about 1,000.

The North Grove included the 'Discovery Tree' noted by Augustus T. Dowd in 1852 and felled in 1853, leaving a giant stump which is the only remainder of the tree. It measured 24 feet (7.3 m) in diameter at its base and was counted by ring count to be 1,244 years old when felled.

In addition to the popular North Grove, the Park also now includes the South Grove, with a 5 mile (8 km) hiking trip through a spectacular grove of giant sequoias in their natural setting. The South Grove includes the 'Agassiz' tree, 74 m tall and 6.8 m diameter 2 m above ground (7.6 m diameter at the base), the largest tree in the Calaveras groves. It is named after zoologist Louis Agassiz (1807-1873).

Other attractions in the Park include the Stanislaus River, Beaver Creek, the Lava Bluff Trail and Bradley Trail.

The Park also houses two main campgrounds with a total of 129 campsites, six picnic areas and hundreds of miles of established trails.

Other activities include cross-country skiing, evening ranger talks, numerous interpretive programs, environmental educational programs, junior ranger programs, hiking, mountain biking, bird watching and summer school activities for school children. Dogs are welcome in the park on leash in developed areas like picnic sites, campgrounds, roads and fire roads (dirt). Dogs are not allowed on the designated trails, nor in the woods in general.