San Juan Archipelago

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The Southern Gulf Islands are highlighted in white; the San Juan Islands are directly to their southeast. Combined, they form the San Juan Archipelago.

The San Juan Archipelago is a group of islands in the Pacific Northwest region of North America. They are located at the meeting point of the Strait of Georgia and the Strait of Juan de Fuca between Vancouver Island, the Olympic Peninsula and the continental mainland. The archipelago is split into two island groups based on national sovereignty. The San Juan Islands are part of the United States Washington state, while the Gulf Islands are part of the Canadian province British Columbia. The Gulf Islands are usually sub-divided into two smaller groups, the Southern and Northern Gulf Islands.

The islands were named by the Spanish Francisco Eliza who explored them in 1790-92. Soon after they were found by the British explorer George Vancouver, and the American, Charles Wilkes. Several sovereignty disputes occurred between Canada and the United States. The border was established in 1872.

Part of a submerged mountain chain, the archipelago has more than 450 islands visible at high tide. Only 14 percent of them are permanently inhabited. The major islands are linked by ferry services, and some have bridges between them or to the mainland. Today, the islands are an important tourist destination with extensive summer resort development. Sea kayaking and orca watching are two primary attractions.

Shaded-relief map of Vancouver Island and parts of British Columbia and Washington state, showing an approximation of the international border.


The Strait of Georgia is the upper body of water running southeasterly, the narrower Puget Sound is at the bottom right, running north-south. The Strait of Juan de Fuca (east-west) meets the two and connects them to the Pacific Ocean (bottom left). The San Juan Archipelago is clustered at the point where the waters meet between Vancouver Island, the Olympic Peninsula and the mainland.

The San Juan Archipelago, from a geological standpoint, includes the Southern Gulf Islands and the San Juan islands. The boundaries delineating the two groups are political, based upon the international border between the U.S. and Canada. They are located in and at the meeting point of the Strait of Georgia and the Strait of Juan de Fuca.

Strait of Georgia

The Strait of Georgia is a strait between Vancouver Island and the mainland Pacific coast of British Columbia, Canada. It is approximately 240 kilometers (150 mi) long and varies in width from 18.5 to 55 km (11.5 to 34 mi).[1]

Archipelagos and narrow channels mark each end of the Strait of Georgia, the Gulf Islands and San Juan Islands in the south, and the Discovery Islands in the north. The main channels to the south are Haro Strait and Rosario Strait, which connect the Strait of Georgia to the Strait of Juan de Fuca. In the north, Discovery Passage is the main channel connecting the Strait of Georgia to Johnstone Strait.

The USGS defines the southern boundary of the Strait of Georgia as a line running from East Point on Saturna Island to Patos Island, Sucia Island, and Matia Island, then to Point Migley on Lummi Island. This line touches the northern edges of Rosario Strait, which leads south to the Strait of Juan de Fuca, and Boundary Pass, which leads south to Haro Strait and the Strait of Juan de Fuca.[2]

The term "Gulf of Georgia" includes other waters than the Georgia Strait proper such as the interinsular straits and channels of the Gulf Islands, and as a region name may refer to communities on the littoral of southern Vancouver Island. As defined by George Vancouver in 1792, the Gulf of Georgia included all the inland waters beyond the eastern end of the Strait of Juan de Fuca, including Puget Sound, Bellingham Bay, the waters around the San Juan Islands, and the Strait of Georgia.[3]

Strait of Juan de Fuca

The Strait of Juan de Fuca is a large body of water about 95 miles (153 km) long[4] forming the principal outlet for the Strait of Georgia and Puget Sound, connecting both to the Pacific Ocean. It provides part of the international boundary between the United States and Canada.

The USGS defines the Strait of Juan de Fuca as a channel. It extends east from the Pacific Ocean between Vancouver Island, British Columbia, and the Olympic Peninsula, Washington, to Haro Strait, San Juan Channel, Rosario Strait, and Puget Sound. The Pacific Ocean boundary is formed by a line between Cape Flattery and Tatoosh Island, Washington, and Carmanah Point (Vancouver Island), British Columbia. Its northern boundary follows the shoreline of Vancouver Island to Gonzales Point, then follows a continuous line east to Seabird Point (Discovery Island), British Columbia, Cattle Point (San Juan Island), Washington, Iceberg Point (Lopez Island), Point Colville (Lopez Island), and then to Rosario Head (Fidalgo Island). The eastern boundary runs south from Rosario Head across Deception Pass to Whidbey Island, then along the western coast of Whidbey Island to Point Partridge, then across Admiralty Inlet to Point Wilson (Quimper Peninsula). The northern coast of the Olympic Peninsula forms the southern boundary of the strait.[4]

Because it is exposed to the generally westerly winds and waves of the Pacific, seas and weather in Juan de Fuca Strait are, on average, rougher than in the more protected waters inland, thereby resulting in small craft advisories being commonplace.


One of the San Juan Islands at Night
Strait of Georgia from Burnaby Mountain, with Galiano Island and Vancouver Island in the distance
Georgia Strait in the morning
One of the San Juan islands
Sunset over the strait
Deception Pass Bridge, connecting Whidbey Island to Pass Island, is on the National Register of Historic Places.
Map of the lands in dispute

The islands of the archipelago and their surrounding waters are rich with ecologically diverse plants and sea life including Garry oaks, wild lilies, kelp beds and Orca whales.

The majority of the San Juan Islands are quite hilly. The highest elevation is Mount Constitution on Orcas Island at 2,410 feet (730 m). There are also some flat areas and valleys, often quite fertile, in between. The coastlines vary between sandy and rocky beaches, shallow and deep harbors, placid and reef-studded bays, and fjords and smooth coastlines. Gnarled, ochre-colored madrona trees (Arbutus) grace much of the shorelines while evergreen fir and pine forests cover large inland areas.

While the nearby Seattle metropolitan area (about 65 miles (105 km) to the south) is known for its frequent rainfall, the islands receive less due to protection by the rain shadow of Olympic Mountains to the southwest.

Summertime high temperatures are around 70 °F (21 °C) while average wintertime lows are in the high thirties and low forties. Snow is infrequent in winter except for the higher elevations, but the islands are subject to high winds at times—those from the northeast sometimes bring brief periods of freezing and Arctic-like windchills.

Beginning in about 1900 the San Juan Islands became infested with European rabbits, an exotic invasive species, as the result of the release of domestic rabbits on Smith Island. Rabbits from the San Juan Islands were used later for several introductions of European rabbits into other, usually midwestern, states.

The Gulf Islands are home to one of the last remaining pockets of Garry oak ecosystems. Today, Garry oak meadows exist in the shallow and exposed soil of valleys, rocky foothills and southern slopes—areas that the settlers of the past 150 years have found unsuitable for agriculture or development.

Only about five percent of Garry oak ecosystems remain in their natural state, landing 91 of the approximately 350 species it supports on British Columbia's list of species at risk. These ecosystems are home to more plant species, such as the camas, than any other terrestrial ecosystem in the province's coastal area.[5]


The islands were part of the traditional area of the Central Coast Salish, which consisted of five linguistically groups: the Squamish, Halkomelem, Nooksack, Northern Straits (which includes the Lummi dialect), and Klallam tribes. Exploration and settlement by Europeans brought smallpox to the area by the 1770s, diminishing the Native populations.


The name "San Juan" was given to the San Juan Islands by the Spanish explorer Francisco de Eliza, who charted the islands in 1791, naming them Isla y Archiepelago de San Juan. The expedition sailed under the authority of the Viceroy of Mexico, Juan Vicente de Güemes Padilla Horcasitas y Aguayo, 2nd Count of Revillagigedo and Eliza named several places for him, including the San Juan Islands and Orcas Island (short for "Horcasitas"). San Juan Island itself was first discovered by a European officer under Eliza's command, Gonzalo López de Haro (for whom Haro Strait is named).

Subsequent explorations of the region by the British, under George Vancouver, and the Americans, under Charles Wilkes, resulted in many of the Spanish names being replaced with English ones. Vancouver's expedition occurred within a year of Eliza's, and Vancouver encountered other Spanish ships and traded information. Thus Vancouver knew of the names given by Eliza's expedition and tended to keep them, although he renamed some things, like the Strait of Georgia.

Wilkes, sailing in 1841, had some British charts, but may not have been aware of the Spanish names and charts. He liberally gave new names to nearly every coastal feature not already named on the charts he had. In 1847, due to the confusion of multiple names on different charts, the British Admiralty reorganized the official charts of the region. The project, led by Henry Kellett, applied only to British territory, which at the time included the San Juan Islands but not Puget Sound.[6]

Boundary disputes and settlement

The Treaty of 1818 set the boundary between the United States and British North America along the 49th parallel of north latitude from Minnesota to the "Stony Mountains"[7] (now known as the Rocky Mountains). West of those mountains was known to the Americans as the Oregon Country and to the British as the Columbia Department or Columbia District of the Hudson's Bay Company. The treaty provided for joint control of that land for ten years. Both countries could claim land and both were guaranteed free navigation throughout.

Joint control steadily grew intolerable for both sides. After a British minister rejected U.S. President James K. Polk's offer to settle the boundary at the 49th parallel north, Democratic expansionists called for the annexation of the entire region up to 54°40', the southern limit of Russian America as established by parallel treaties between the Russian Empire and the U.S. (1824) and Britain (1825). However, after the outbreak of the Mexican-American War diverted U.S. attention and resources, a compromise was reached.

The treaty was negotiated by U.S. Secretary of State James Buchanan, who later became president, and Richard Pakenham, envoy to the United States and member of the Privy Council of the United Kingdom for Queen Victoria. The Oregon Treaty was signed on June 15, 1846.

The treaty set the U.S. and British North American border at the 49th parallel with the exception of Vancouver Island, which was retained in its entirety by the British and constituted, with all coastal islands, as the Colony of Vancouver Island in 1849. The U.S. portion of the region was organized as Oregon Territory on August 14, 1848, with Washington Territory being formed from it in 1853. The British portion remained unorganized until 1858. When the Colony of British Columbia joined Canada in 1871, the 49th Parallel and marine boundaries established by the Oregon Treaty became the U.S.-Canadian border.

While both sides agreed that all of Vancouver Island would remain British, the treaty wording was left vague enough as to put the boundary between modern-day Gulf Islands and San Juan Islands in dispute. In 1859, this lack of clarity of the maritime border in the treaty later led to the bloodless war known as the Pig War over the ownership of the San Juan Islands. The border was finally established in 1872.

Island listing

Major islands in the San Juans
North Pender, Mayne and Galiano Islands
A view of North Pender Island's shoreline
Arbutus trees and sandstone beaches are common in the Gulf Islands.
  • Aleegria Island
  • Allan Island
  • Anderson Island
  • Armitage Island
  • Barnes Island
  • Barren Island
  • Battleship Island
  • Bell Island
  • Blakely Island
  • Blind Island
  • Boulder Island
  • Brown Island
  • Buck Island
  • Burrows Island
  • Cactus Islands
  • Canoe Island
  • Castle Island
  • Cemetery Island
  • Center Island
  • Clark Island
  • Cliff Island
  • Colville Island
  • Coon Island
  • Crab Island
  • Crane Island
  • Cypress Island
  • Deadman Island
  • Decatur Island
  • Dinner Island
  • Doe Island
  • Double Island
  • Eliza Island
  • Ewing Island
  • Fawn Island
  • Fidalgo Island
  • Flattop Island
  • Flower Island
  • Fortress Island
  • Freeman Island
  • Frost Island
  • Goose Island
  • Gossip Island
  • Guemes Island
  • Guss Island
  • Hall Island
  • Hat Island
  • Henry Island
  • Iceberg Island
  • James Island
  • Johns Island
  • Jones Island
  • Justice Island
  • Little Island
  • Little Patos Island
  • Little Sister Island
  • Lone Tree Island
  • Lopez Island
  • Low Island
  • Lummi Island
  • Matia Island
  • Mcconnell Island
  • Minor Island
  • Nob Island
  • North Finger Island
  • Obstruction Island
  • O'Neal Island
  • Orcas Island
  • Patos Island
  • Pearl Island
  • Picnic Island
  • Pointer Island
  • Pole Island
  • Portage Island
  • Posey Island
  • Puffin Island
  • Ram Island
  • Reef Island
  • Rim Island
  • Ripple Island
  • Rum Island
  • Samish Island
  • San Juan Island
  • Satellite Island
  • Sentinel Island
  • Shaw Island
  • Sheep Island
  • Sinclair Island
  • Skull Island
  • Small Island
  • Smith Island
  • South Finger Island
  • Spieden Island
  • Strawberry Island
  • Stuart Island
  • Sucia Island
  • Swirl Island
  • Towhead Island
  • Trump Island
  • Turn Island
  • Vendovi Island
  • Victim Island
  • Waldron Island
  • Wasp Islands
  • Willow Island
  • Yellow Island

Southern Gulf Islands

The southern Gulf Islands include hundreds of islands and islets. The major islands in alphabetical order are:

  • Gabriola Island
  • Galiano Island
  • Kuper Island
  • Mayne Island
  • North and South Pender Islands
  • Saltspring Island
  • Saturna Island
  • Thetis Island
  • Valdes Island
Northern Gulf Islands

The major islands in alphabetical order are:

  • Denman Island
  • Hornby Island
  • Lasqueti Island
  • Texada Island

Cortes Island, and Quadra Island are sometimes considered part of the Gulf Islands, but as they are not in the Georgia Strait they are more properly considered part of the Discovery Islands.

Looking ahead

Both the Gulf Islands and the San Juan Islands which make up the San Juan Archipelago have been inhabited seasonally for about 2000 years. They were used as summer homes by people of the Lummi, Samish, and Songish tribes. Today, about 60 of these islands are still populated, though in most cases, sparsely.[8]

While they are located in a northern region, they lie in the rain shadow of the Olympic Mountains and have a moderate and relatively dry climate. The temperature is moderated by the sea and they are protected from winds and storms by virtue of their relative enclosure within the straits.

Until the 1970s, the islands were quiet and little known outside the Pacific Northwest. In the 1980s, they began to attract tourists and became a popular destination for ocean cruises. The population density however, remains low.

Surrounded by sheltered waters, strong tides, and dramatic coastlines, coupled with a pleasant climate, varied marine life, and unobstructed views, they will continue to offer a peaceful retreat for many. While they have summer resort development, their relative remoteness places somewhat of a guarantee against over-development of year-round habitats; a positive aspect for the natural environment.


  1. R.G. Gustafson, et al. November 2000. Environmental History and Features of Puget Sound, National Oceanic and Atmospheric Administration—Northwest Fisheries Science Center. Retrieved February 19, 2009.
  2. US Geological Survey. USGS GNIS: Strait of Georgia Retrieved February 19, 2009.
  3. John E. Roberts. 2005. A Discovery Journal of George Vancouver's First Survey Season on the Coasts of Washington and British Columbia, 1792: Including the Work with the Spanish Explorers Galiano and Valdés (Victoria, B.C.: Trafford, 2005, ISBN 9781412070973), 72.
  4. 4.0 4.1 US Geological Survey, USGS GNIS: Strait of Juan de Fuca Retrieved February 19, 2009.
  5. Kathryn Carlson, Habitat loss and invading exotic species are threatening what remains of the native vegetation found in the Garry oak ecosystem, Canadian Geographic. Retrieved February 19, 2009.
  6. James W. Phillips, Washington State Place Names (Seattle: Univ. of Washington, 1972, ISBN 0295951583).
  7. Université de Montréal, Convention of Commerce between His Majesty and the United States of America.—Signed at London, 20th October, 1818. Retrieved February 19, 2009.
  8. San Juan Islands Guide, The San Juan Islands. Retrieved February 20, 2009.

ISBN links support NWE through referral fees

  • Canadian Geographic. Come to the Islands. February 20, 2009.
  • Downen, Mark R. 1996. Environmental History and Ecology of the San Juan Archipelago. Bellingham, WA: Huxley College of Environmental Studies, Western Washington University. OCLC 49752934.
  • Gardner, Mark. 2001. The San Juan Islands: Crown Jewels of the Pacific Coast. Seattle: Sasquatch Books. ISBN 9781570612817.
  • Johnston, Martina. 1927. The Acquisition of the San Juan archipelago. OCLC 41704325.
  • Parks Canada. Gulf Islands National Park Reserve. Retrieved February 20, 2009.

External links

All links retrieved December 22, 2022.


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