Giants near the Stanislaus River Calaveras Big Trees State Park beckons ARNOLD — The easiest giant sequoias to access in the entire Sierra are just a two-hour drive from here. Three miles north of Arnold off Highway 4 you’ll find the colossal trees of Calaveras Big Trees State Park that stand in quiet testimony to prehistoric times. These massive relics, which can reach a height of 325 feet and a diameter of 33 feet, are descended from trees that were standing when dinosaurs roamed Earth, and birds, mammals and flowering plants began to appear.