The Strait of Georgia is 220 km (135 miles) long and from 25 to 55 km wide (15 to 35 miles). Some people call it the "Gulf of Georgia", as that was the name Captain Vancouver first gave it - and the reason why the hundreds of islands here are called the Gulf Islands. The Strait is fed by freshwater from the huge Fraser River system, which carries rich silt and fresh water far across the Strait. This 850-mile long river drains over 20 million hectares - one quarter of BC. It has the largest salmon runs in North America and its estuary is a vital stopover spot for migrating birds from three continents. Aside from the mild climate, one of the main reasons that the Strait of Georgia is so rich in wildlife is because of the Fraser River and the fresh water, silt and nutrients it carries far into the Strait. The Strait has a wide variety of habitats. You can find pristine sandy beaches, rocky shores, steep cliffs, sandstone shelves, mudflats, and deep fjords - all these and more. There are many other important estuaries in the Strait of Georgia. As well as being vital for fish and wildlife, salt marshes and other wetland vegetation serve as the "kidneys" of the ecosystem, trapping and holding water and air-borne contaminants such as the sulfur in acid rain. Georgia Strait is important not only in a biological sense, but is essential to the human population of the region for income, transportation, recreation and spiritual sustenance. These waters have been important for commercial, sports and aboriginal fishing. The shellfish industry is also economically important, with many shellfish growers located in communities around the Strait. Many others work on these waters in transport, towing and other forms of marine commerce. Tourism is the fastest-growing industry and now probably the most important one to the region.