Gastineau Channel is a channel

Strait

A strait or straits is a narrow, typically navigable channel of water that connects two larger, navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not...

 between the mainland of the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 and Douglas Island

Douglas Island

Douglas Island is a tidal island in the U.S. state of Alaska, just west of downtown Juneau and east of Admiralty Island. It is separated from mainland Juneau by the Gastineau Channel. The Juneau-Douglas Bridge, connecting the island with Juneau, provides a two lane road to and from the island and...

 in the Alexander Archipelago

Alexander Archipelago

The Alexander Archipelago is a long archipelago, or group of islands, of North America off the southeastern coast of Alaska. It contains about 1,100 islands, which are the tops of the submerged coastal mountains that rise steeply from the Pacific Ocean. Deep channels and fjords separate the...

 of southeastern Alaska. It separates Juneau

Juneau, Alaska

The City and Borough of Juneau is a unified municipality located on the Gastineau Channel in the panhandle of the U.S. state of Alaska. It has been the capital of Alaska since 1906, when the government of the then-District of Alaska was moved from Sitka as dictated by the U.S. Congress in 1900...

 on the mainland side from Douglas

Douglas, Alaska

Douglas, Alaska is an area on Douglas Island in southeastern Alaska. Itoriginated in 1881 as a place providing services to miners of the nearby Treadwell gold mine, and was incorporated as a city in 1902. Douglas was once a larger town than neighboring Juneau, but dwindled in the early 1900s as...

 (now part of Juneau), on Douglas Island. The first European to sight the channel was Joseph Whidbey

Joseph Whidbey

Joseph Whidbey was a member of the Royal Navy who served on the Vancouver Expedition 1791–1795, and later achieved renown as a naval engineer. He is notable for having been the first European to discover and chart Admiralty Island in the Alexander Archipelago in 1794.Little is recorded of...

 early in August 1794, first from the south and later from the west. It was probably named for John Gastineau, an English

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 Civil Engineer

Civil engineer

A civil engineer is a person who practices civil engineering; the application of planning, designing, constructing, maintaining, and operating infrastructures while protecting the public and environmental health, as well as improving existing infrastructures that have been neglected.Originally, a...

 and Surveyor

Surveying

See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

.

The channel is navigable by large ships only from the southeast as far as the bridge connecting Douglas Island with the mainland. Between the bridge and the airport in Mendenhall Valley

Mendenhall Valley

Mendenhall Valley is an area of Juneau in the U.S. state of Alaska. The valley, named for physicist and meteorologist Thomas Corwin Mendenhall, was formed by Mendenhall Glacier over the course of roughly three thousand years...

, the channel becomes navigable only to smaller craft and only at high tide.

The channel is becoming increasingly unnavigable as there has been a marked increase in silt build up. It has been argued that this a consequence of Global Warming

Global warming

Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

 on the nearby Mendenhall Glacier

Mendenhall Glacier

Mendenhall Glacier is a glacier about long located in Mendenhall Valley, about from downtown Juneau in the southeast area of the U.S. state of Alaska....

. If current trends continue, it is possible the channel may be entirely blocked and filled with dry land.