Antelope Island, with an area of 42 square miles, is the largest of ten islands located within the Great Salt Lake in Utah. The island lies in the southeastern portion of the lake, near Salt Lake City and Davis County, and becomes a peninsula when the lake is at extremely low levels. It is protected as Antelope Island State Park.

The first known non-natives to visit the island were John C. Frémont and Kit Carson during exploration of the Great Salt Lake in 1845, who "rode on horseback over salt from the thickness of a wafer to twelve inches" and "were informed by the Indians that there was an abundance of fresh water on it and plenty of antelope". It is said they shot a pronghorn antelope on the island and in gratitude for the meat they named it Antelope Island.

Antelope Island has natural scenic beauty and holds populations of pronghorn, bighorn sheep, American bison, porcupine, badger, coyote, bobcat, mule deer, and millions of waterfowl. The bison were introduced to the island in 1893, and the Antelope Island bison herd has proven to be a valuable genetic pool for bison breeding and conservation purposes. The bison do well, because much of the island is covered by dry, native grassland.

The geology of Antelope Island consists mostly of alluvial plains with prairie grassland on the north, east and south of the island, along with a mountainous central area of older Precambrian metamorphic and igneous rocks and late Precambrian to Paleozoic sedimentary rocks, covered by a thin layer of Quaternary lake deposits, colluvium and alluvium. The Precambrian deposits on Antelope Island are some of the oldest rocks in the United States, older even than the Precambrian rocks at the bottom of the Grand Canyon.

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Antelope Island State Park is surrounded by the Great Salt Lake. The lake is the last remaining part of a vast inland Pleistocene Sea, Lake Bonneville. At more than 1,000 feet and more than 19,691 square miles in area, the lake was nearly as large as Lake Michigan and significantly deeper. With the change in climate, the lake began drying up, leaving Great Salt Lake, Utah Lake, Sevier Lake, and Rush Lake as remnants. As Lake Bonneville receded it left behind the Great Basin, which is made of narrow mountain ranges and broad valleys, known locally as basins. The Great Salt Lake is endorheic and has very high salinity, far saltier than sea water. The Jordan, Weber, and Bear rivers deposit around 1.1 million tons of minerals in the lake each year. Due to its high salt concentration, most people can easily float in the lake as a result of the high density of the water. The Great Salt Lake is the fourth-largest terminal lake in the world, in an average year the lake covers an area of approximately 1,700 square miles but the lake's size fluctuates due to low water levels. For example, in 1963 it reached its lowest recorded level at 950 square miles, but in 1987 the surface area was at the historic high of 3,300 square miles Great Salt Lake does not support fish but does support large numbers of brine shrimp and brine flies which provide food for visiting waterfowl. Because of the high salinity, the island is mostly without readily available fresh water.

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Antelope Island is 28,022 acres and is 15 miles long and 4.5 miles at its widest point. The island is in the midst of the Great Basin between the Wasatch and Sierra Nevada Mountain ranges. The highest point on the island is Frary Peak at 6,589 feet above sea level. It is one of eight important islands in the lake. The others are Badger, Bird, Dolphin, Gunnison, Carrington, Stansbury and Fremont. Two of the major islands, Gunnison and Bird, and two minor islands, Egg and White Rock are rookeries and as such are protected. Visitor access is not permitted on the protected islands.

The rocks in and around the Fielding Garr Ranch are some of the oldest rocks in the United States. At 2.7 billion years old, they are older than the rocks in the bottom of the Grand Canyon. Tintic quartzite is found on the northern third of the island. It is about 550 million years old. Tufa rocks on the island are some of the youngest rocks in the United States. They were deposited as Lake Bonneville receded between 10,000 - 15,000 years ago. The tufa rocks resemble concrete and are in the vicinity of Buffalo Point.

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Photo is taken at Antelope Island Campground looking North Bound.

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