Sherman Island is an island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 in the Sacramento-San Joaquin River Delta at the confluence of the two rivers in Sacramento County, California

Sacramento County, California

Sacramento County is a county in the U.S. state of California. Its county seat is Sacramento, which is also the state capital. As of 2010 the county had a population of 1,418,788....

, two kilometres northeast of Antioch

Antioch, California

Antioch is a city in Contra Costa County, California. Located in the East Bay region of the San Francisco Bay Area along the San Joaquin-Sacramento River Delta, it is a suburb of San Francisco and Oakland. The city's population was 102,372 at the U.S...

. The 5500 ha (13,590.8 acre) island is the meeting point of Sacramento-

Sacramento County, California

Sacramento County is a county in the U.S. state of California. Its county seat is Sacramento, which is also the state capital. As of 2010 the county had a population of 1,418,788....

, Solano-

Solano County, California

Solano County is a county located in Bay-Delta region of the U.S. state of California, about halfway between San Francisco and Sacramento and is one of the nine San Francisco Bay Area counties. The county's population was reported by the U.S. Census to be 413,344 in 2010...

, and Contra Costa-Counties

Contra Costa County, California

Contra Costa County is a primarily suburban county in the San Francisco Bay Area of the U.S. state of California. As of the 2010 census, it had a population of 1,049,025...

, and is bordered on the north and northwest by the Sacramento River

Sacramento River

The Sacramento River is an important watercourse of Northern and Central California in the United States. The largest river in California, it rises on the eastern slopes of the Klamath Mountains, and after a journey south of over , empties into Suisun Bay, an arm of the San Francisco Bay, and...

, on the northeast by Three Mile Slough, and on the east, and south west by the San Joaquin River

San Joaquin River

The San Joaquin River is the largest river of Central California in the United States. At over long, the river starts in the high Sierra Nevada, and flows through a rich agricultural region known as the San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean...

.

The southwest of the island features a large marsh

Marsh

In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....

y area and Sherman Lake where there is fishing and other water sports, particularly windsurfing and kite boarding.