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Tongass Narrows is a Y-shaped channel, part of Southeast Alaska's Inside Passage. The waterway forms part of the Alaska Marine Highway and as such, is used by charter, commercial fishing, and recreational vessels, as well as commercial freight barges and tanks, kayaks and passenger ferries. A proposal to build the Gravina Island Bridge across the Tongass Narrows was shelved due to a national-level controversy over the "bridge to nowhere". ==Geography== Tongass Narrows is defined as the water body that extends from the Revillagigedo Channel to the Gravina Island in Clarence Strait. It is shaped as a "Y", split into two channels by Pennock Island.〔 At its northern end is Clarence Strait. In the southeast it extends from Nichols Passage to Guard Island. The eastern side is bounded by Revillagigedo Island and the west by Gravina Island. The eastern side of the narrows includes the cities of Saxman and Ketchikan. Ketchikan International Airport is located on Gravina Island. The channel extends in a generally northwest direction for about . About westward of East Clump islet, the width of Tongass Narrows is , the shoal water on the north side extending out from the high-water mark. In mid-channel, the depth is from 15 to 26 fathoms (). The north shore of Tongass Narrows is steep and heavily wooded. The south shores are low, flat, and wooded, with occasional open ground for back, where the land rises to the California Ridge. The Tongass Narrows is part of the Alaska Marine Highway system. Many types of vessels operate on the channel, such as charter, commercial fishing, and recreational vessels, as well as commercial freight barges and tanks, kayaks and passenger ferries. There is also extensive floatplane traffic on the Narrows, as Ketchikan is the regional center for air transportation to isolated communities.〔(About Ketchikan, Alaska ), Allen Marine Tours〕 Maritime restrictions are most prevalent around Clam Cove (West Channel), Idaho Rock to the Coast Guard Base (East Channel), and Danger Island to Bar Harbor (North Channel).〔 The geological formation of "green stone schist, Paleozoic" is noted on the narrows near Ketchikan on its eastern side and also on the Gravina Island. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tongass Narrows」の詳細全文を読む スポンサード リンク
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