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Pole of inaccessibility

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Map of distance to the nearest coastline[1] (including oceanic islands, but not lakes) with red spots marking the poles of inaccessibility of main landmasses, Great Britain, and the Iberian Peninsula, and a blue dot marking the oceanic pole of inaccessibility. Thin isolines are 250 km (160 mi) apart; thick lines 1,000 km (620 mi). Mollweide projection.

A pole of inaccessibility with respect to a geographical criterion of inaccessibility marks a location that is the most challenging to reach according to that criterion. Often it refers to the most distant point from the coastline, implying a maximum degree of continentality or oceanity. In these cases, a pole of inaccessibility can be defined as the center of the largest circle that can be drawn within an area of interest without encountering a coast. Where a coast is imprecisely defined, the pole will be similarly imprecise.

Northern pole of inaccessibility

Northern pole of inaccessibility

The Northern pole of inaccessibility, sometimes known as the Arctic pole, is located on the Arctic Ocean pack ice at a distance farthest from any land mass. The original position was wrongly believed to lie at 84°03′N 174°51′W. It is not clear who first defined this point but it may have been Sir Hubert Wilkins, who wished to traverse the Arctic Ocean by aircraft, in 1927. He was finally successful in 1928. In 1968 Sir Wally Herbert came very close to reaching what was then considered to be the position by dogsled but by his own account, "Across The Roof Of The World", did not make it due to the flow of sea ice. In 1986, an expedition of Soviet polar scientists led by Dmitry Shparo claimed to reach the original position by foot during a polar night.[citation needed]

In 2005, explorer Jim McNeill asked scientists from National Snow and Ice Data Center and Scott Polar Research Institute to re-establish the position using modern GPS and satellite technology. This was published as a paper in the Polar Record, Cambridge University Press in 2013.[2] McNeill launched his own, unsuccessful, attempt to reach the new position in 2006, whilst measuring the depth of sea-ice for NASA.[3] In 2010 he and his Ice Warrior team were thwarted again by the poor condition of the sea ice.[4]

The new position lies at 85°48′N 176°9′W, 1,008 km from the three closest landmasses: It is 1008 km from the nearest land, on Henrietta Island in the De Long Islands, at Arctic Cape on Severnaya Zemlya, and on Ellesmere Island. It is over 200 km from the originally accepted position.[5] Due to constant motion of the pack ice, no permanent structure can exist at this pole. As of February 2021, McNeill said that, as far as he could ascertain, no one had reached the new position of the Northern Pole of Inaccessibility - certainly not from the last landfall across the surface of the ocean and it remains an important scientific transect.

Southern pole of inaccessibility

The old Soviet Pole of Inaccessibility Station, revisited by Team N2i on 19 January 2007

The southern pole of inaccessibility is the point on the Antarctic continent most distant from the Southern Ocean. A variety of coordinate locations have been given for this pole. The discrepancies are due to the question of whether the "coast" is measured to the grounding line or to the edges of ice shelves, the difficulty of determining the location of the "solid" coastline, the movement of ice sheets and improvements in the accuracy of survey data over the years, as well as possible topographical errors.

The pole of inaccessibility commonly refers to the site of the Soviet Union research station mentioned below, which was constructed at 82°06′S 54°58′E / 82.100°S 54.967°E / -82.100; 54.967 (Pole of Inaccessibility (WMO))[6] (though some sources give 83°06′S 54°58′E / 83.100°S 54.967°E / -83.100; 54.967 (South Pole of Inaccessibility (IPHC))[7]). This lies 1,301 km (808 mi) from the South Pole, at an elevation of 3,718 m (12,198 ft). Using different criteria, the Scott Polar Research Institute locates this pole at 85°50′S 65°47′E / 85.833°S 65.783°E / -85.833; 65.783 (South Pole of Inaccessibility (SPRI)).[8]

Using recent datasets and cross-confirmation between the adaptive gridding and B9-Hillclimbing[9] methods discussed below, Rees et al. (2021)[10] identify two poles of inaccessibility for Antarctica: an "outer" pole defined by the edge of Antarctica's floating ice shelves and an "inner" pole defined by the grounding lines of these sheets. They find the Outer pole to be at 83°54′14″S 64°53′24″E / 83.904°S 64.890°E / -83.904; 64.890 (Antarctia's Outer Pole of Inaccessibility), 1,590.4 km (988.2 mi) from the ocean, and the Inner pole to be at 83°36′36″S 53°43′12″E / 83.610°S 53.720°E / -83.610; 53.720 (Antarctia's Inner Pole of Inaccessibility), 1,179.4 km (732.8 mi) from the grounding lines.

The southern pole of inaccessibility is far more remote and difficult to reach than the geographic South Pole. On 14 December 1958, the 3rd Soviet Antarctic Expedition for International Geophysical Year research work, led by Yevgeny Tolstikov, established the temporary Pole of Inaccessibility Station (Polyus Nedostupnosti) at 82°06′S 54°58′E / 82.100°S 54.967°E / -82.100; 54.967 (Pole of Inaccessibility Station). A second Russian team returned there in 1967. Today, a building still remains at this location, marked by a bust of Vladimir Lenin that faces toward Moscow, and protected as a historical site.

On 11 December 2005, at 7:57 UTC, Ramón Hernando de Larramendi, Juan Manuel Viu, and Ignacio Oficialdegui, members of the Spanish Transantarctic Expedition, reached for the first time in history the southern pole of inaccessibility at 82°53′14″S 55°04′30″E / 82.88722°S 55.07500°E / -82.88722; 55.07500 (British Antarctic Survey-accredited Pole of Inaccessibility), updated that year by the British Antarctic Survey. The team continued their journey toward the second southern pole of inaccessibility, the one that accounts for the ice shelves as well as the continental land, and they were the first expedition to reach it, on 14 December 2005, at 83°50′37″S 65°43′30″E / 83.84361°S 65.72500°E / -83.84361; 65.72500 (British Antarctic Survey-accredited Pole of Inaccessibility). Both achievements took place within an ambitious pioneer crossing of the eastern Antarctic Plateau that started at Novolazarevskaya Station and ended at Progress Base after more than 4,500 km (2,800 mi). This was the fastest polar journey ever achieved without mechanical aid, with an average rate of around 90 km (56 mi) per day and a maximum of 311 km (193 mi) per day, using kites as their power source.[11][12][13][14]

On 4 December 2006, Team N2i, consisting of Henry Cookson, Rupert Longsdon, Rory Sweet and Paul Landry, embarked on an expedition to be the first to reach the historic pole of inaccessibility location without direct mechanical assistance, using a combination of traditional man hauling and kite skiing. The team reached the old abandoned station on 19 January 2007, rediscovering the forgotten statue of Lenin left there by the Soviets some 48 years previously.[15] The team found that only the bust on top of the building remained visible; the rest was buried under the snow.[16] The explorers were picked up from the spot by a plane from Vostok base, flown to Progress Base and taken back to Cape Town on the Akademik Fyodorov, a Russian polar research vessel.[16]

On 27 December 2011, Sebastian Copeland and partner Eric McNair-Laundry also reached the 82°06′S 54°58′E / 82.100°S 54.967°E / -82.100; 54.967 (Pole of Inaccessibility Station) southern pole of inaccessibility. They were the first to do so without resupply or mechanical support, departing from Novolazarevskaya Station on their way to the South Pole to complete the first East/West crossing of Antarctica through both poles, over 4,000 km (2,485 mi).[17]

As mentioned above, due to improvements in technology and the position of the continental edge of Antarctica being debated, the exact position of the best estimate of the pole of inaccessibility may vary. However, for the convenience of sport expeditions, a fixed point is preferred, and the Soviet station has been used for this role. This has been recognized by Guinness World Records for Team N2i's expedition in 2006–2007.[18]

Oceanic pole of inaccessibility

Location of Point Nemo in relation to three closest coastline points

The oceanic pole of inaccessibility, also known as Point Nemo, is located at roughly 48°52.6′S 123°23.6′W / 48.8767°S 123.3933°W / -48.8767; -123.3933[19] and is the place in the ocean that is farthest from land. It represents the solution to the "longest swim" problem.[20] This problem poses that there is one place in an ocean on earth where, if a person fell overboard while on a ship at sea, they would be at a point that is the longest distance to any land in any direction. It lies in the South Pacific Ocean, and is equally distant from the three closest land vertices which are each roughly 2688km away. Those vertices are Pandora, an islet that, along with others forms the Ducie Island Atoll, (part of the Pitcairn Islands) to the north; Motu Nui (part of the Easter Islands) to the northeast; and Maher Island (near the larger Siple Island, off the coast of Marie Byrd Land, Antarctica) to the south.[19] The exact coordinates of Point Nemo depend on what the exact coordinates of these three islands are since the nature of the "longest swim" problem means that the ocean-point is equally far from each.[20]

The area is so remote that - as with any location more than 400 kilometers from an inhabited area - sometimes the closest human beings are astronauts aboard the International Space Station when it passes overhead.[21][22] Point Nemo was first discovered by survey engineer Hrvoje Lukatela in 1992.[22] In 2022, Lukatela recalculated the coordinates of Point Nemo using Open Street Map data as well as Google Maps data in order to compare those results with the coordinates he first calculated using Digital Chart of the World data.[20]

The point and the areas around it have attracted literary and cultural attention. It is known as Point Nemo, a reference to Jules Verne's Captain Nemo from the novel 20,000 Leagues Under the Sea.[21][19] This novel was a childhood favorite of Lukatela's so he named it after Captain Nemo.[19][23]

The general area plays a major role in the 1928 short story "The Call of Cthulhu" by H. P. Lovecraft, as holding the location of the fictional city of R'lyeh, although this story was written 66 years before the identification of Point Nemo.[21] The area is nowadays known as a "spacecraft cemetery" because hundreds of decommissioned satellites, space stations, and other spacecraft have been made to fall there upon re-entering the atmosphere, to lessen the risk of hitting inhabited locations[24] or maritime traffic. The International Space Station (ISS) is planned to crash into Point Nemo in 2031.[25][26]

Point Nemo is relatively lifeless; its location within the South Pacific Gyre blocks nutrients from reaching the area, and being so far from land it gets little nutrient run-off from coastal waters.[21]

To the west the region of the South Pacific Ocean is also the site of the geographic center of the water hemisphere, at 47°24′42″S 177°22′45″E / 47.411667°S 177.379167°E / -47.411667; 177.379167 near New Zealand's Bounty Islands. The geographic center of the Pacific Ocean lies further north-west where the Line Islands begin, west from Starbuck Island at 4°58′S 158°45′W / 4.97°S 158.75°W / -4.97; -158.75.[27]

Continental poles of inaccessibility

Eurasia

Proposed continental pole of inaccessibility at 46°17′N 86°40′E
Distance to the sea in Asia, showing the two candidate locations for Eurasian pole of inaccessibility.

The Eurasian pole of inaccessibility (EPIA) is located in northwestern China, near the Kazakhstan border. It is also the furthest possible point on land from the ocean, given that Eurasia (or even merely Asia alone) is the largest continent on Earth.

Earlier calculations suggested that it is 2,645 km (1,644 mi) from the nearest coastline, located at 46°17′N 86°40′E / 46.283°N 86.667°E / 46.283; 86.667 (Proposed Continental Pole of Inaccessibility), approximately 320 km (200 mi) north of the city of Ürümqi, in the Xinjiang Autonomous Region of China, in the Gurbantünggüt Desert. The nearest settlements to this location are Hoxtolgay Town at 46°34′N 85°58′E / 46.567°N 85.967°E / 46.567; 85.967 (Hoxtolgay), about 50 km (31 mi) to the northwest, Xazgat Township (Chinese: 夏孜盖乡; pinyin: Xiàzīgài xiāng) at 46°20′N 86°22′E / 46.333°N 86.367°E / 46.333; 86.367 (Xazgat), about 20 km (12 mi) to the west, and Suluk at 46°15′N 86°50′E / 46.250°N 86.833°E / 46.250; 86.833 (Suluk), about 10 km (6.2 mi) to the east.[citation needed]

However, the previous pole location disregards the Gulf of Ob as part of the oceans, and a 2007 study[1] proposes two other locations as the ones farther from any ocean (within the uncertainty of coastline definition): EPIA1 44°17′N 82°11′E / 44.29°N 82.19°E / 44.29; 82.19 and EPIA2 45°17′N 88°08′E / 45.28°N 88.14°E / 45.28; 88.14, located respectively at 2,510±10 km (1560±6 mi) and 2,514±7 km (1,562±4 mi) from the oceans.[1] These points lie in a close triangle about the Dzungarian Gate, a significant historical gateway to migration between the East and West. EPIA2 is located near a settlement called K̂as K̂îr Su in a region named K̂îzîlk̂um (قىزىلقۇم) in the Karamgay Township [zh], Burultokay County.

Elsewhere in Xinjiang, the location 43°40′52″N 87°19′52″E / 43.68111°N 87.33111°E / 43.68111; 87.33111 in the southwestern suburbs of Ürümqi (Ürümqi County) was designated by local geography experts as the "center point of Asia" in 1992, and a monument to this effect was erected there in the 1990s. The site is a local tourist attraction.[28]

Coincidentally, the continental and oceanic poles of inaccessibility have a similar radius; the Eurasian poles EPIA1 and EPIA2 are about 178 km (111 mi) closer to the ocean than the oceanic pole is to land.

Africa

In Africa, the pole of inaccessibility is at 5°39′N 26°10′E / 5.65°N 26.17°E / 5.65; 26.17, 1,814 km (1,127 mi) from the coast,[1] near the town of Obo in the Central African Republic and close to the country's tripoint with South Sudan and the Democratic Republic of the Congo.

North America

The North-West portion of the North American Pole of Inaccessibility.

In North America, the continental pole of inaccessibility is on the Pine Ridge Reservation in southwest South Dakota about 11 km (7 mi) north of the town of Allen, 1,650 km (1,030 mi) from the nearest coastline at 43°22′N 101°58′W / 43.36°N 101.97°W / 43.36; -101.97 (Pole of Inaccessibility North America).[1] The pole was marked in 2021 with a marker that represents the 7 Lakota Values and the four colors of the Lakota Medicine Wheel.[29]

South America

In South America, the continental pole of inaccessibility is in Brazil at 14°03′S 56°51′W / 14.05°S 56.85°W / -14.05; -56.85 (Continental Pole of Inaccessibility in South America), near Arenápolis, Mato Grosso,[1] 1,504 km (935 mi) from the nearest coastline. In 2017, the Turner Twins became the first adventurers to trek to the South American Pole of Inaccessibility.[30]

Australia

Australian Pole of Inaccessibility

In Australia, the continental pole of inaccessibility is located either at 23°10′S 132°16′E / 23.17°S 132.27°E / -23.17; 132.27 (Continental Pole of Inaccessibility of Australia)[1] or at 23°2′S 132°10′E / 23.033°S 132.167°E / -23.033; 132.167 (Australian Pole of Inaccessibility),[31] 920 km (570 mi) from the nearest coastline, approximately 161 km (100 miles) west-northwest of Alice Springs. The nearest town is Papunya, Northern Territory, about 30 km (19 mi) to the southwest of both locations.

Methods of calculation

As detailed below, several factors determine how a pole is calculated using computer modeling.

Poles are calculated with respect to a particular coastline dataset. Commonly used datasets are the Global Self-consistent, Hierarchical, High-resolution Geography Database[32] as well as OpenStreetMap planet dumps.

Next, a distance function must be determined for calculating distances between coastlines and potential Poles. Some works tended to project data onto planes or perform spherical calculations; more recently, other works have used different algorithms and high-performance computing with ellipsoidal calculations.[9]

Finally, an optimization algorithm must be developed. Several works[1][2] use an adaptive grid method. In this method, a grid of, e.g., 21×21 points is created. Each point's distance from the coastline is determined and the point farthest from the coast identified. The grid is then recentered on this point and shrunk by some factor. This process iterates until the grid becomes very small. Some authors claim this adaptive grid method is problematic as it is not guaranteed to find the farthest point from a coastline. A more recent method, B9-Hillclimbing, uses random-restart hill climbing, simulated annealing, and k-d trees to find the farthest points from coastlines.[9] This Hillclimbing method has not demonstrated, however, how it is consistent with the foundational idea that a pole of inaccessibility must, by definition, have only three closest shoreline points.

To date there has been no meta-study of the various works, and the algorithms and datasets they use, that compares their calculations of poles of inaccessibility to satellite determined calculations. Therefore no conclusion is possible at this time as to which methodology is more accurate in calculating a pole of inaccessibility.

List of poles of inaccessibility

Poles of Inaccessibility, as determined by some authors, are listed in the table below. This list is incomplete and may not capture all works done to date.

Poles of inaccessibility as calculated by various authors
Pole Latitude
(° N)
Longitude
(° E)
Distance from
coast (km)
Dataset Projection Method Reference
Africa 5.65 26.17 1814 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Africa 5.6413 26.1533 1814.5158 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Africa 5.6589 26.1295 1815.4150 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Antarctica -83.904 64.890 1590.36 ADDv7.2 "Outer" WGS84 B9-Hillclimbing Rees (2021)[10]
Antarctica -83.610 53.720 1179.40 ADDv7.2 "Inner" WGS84 B9-Hillclimbing Rees (2021)[10]
Antarctica -77.3963 105.3855 1136.2129 GSHHG v2.3.6 (L1+L6). Erroneous. WGS84 B9-Hillclimbing Barnes (2019)[9]
Antarctica -78.2633 103.6340 1273.2928 GSHHG v2.3.6 (L1+L5). Erroneous. WGS84 B9-Hillclimbing Barnes (2019)[9]
Arctic Pole 85.7911 176.2386 1008.9112 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Arctic Pole 85.8015 176.1423 1007.6777 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Arctic Pole 85.802 176.149 1008 GSHHG 2014 WGS84 B9-Hillclimbing Rees (2014)[2]
Atlantic Ocean 24.1851 -43.3704 2033.8849 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Atlantic Ocean 24.1923 -43.3728 2033.5187 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Australia -23.17 132.27 928 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Australia -23.1732 132.2759 925.4459 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Australia -23.1948 132.1727 921.9290 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Eurasia 1 45.28 88.14 2514 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Eurasia 1 45.3413 88.2483 2513.9415 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Eurasia 1 45.4435 88.3172 2509.9536 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Eurasia 2 44.29 82.19 2510 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Eurasia 2 44.3184 82.1144 2509.9685 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Eurasia 2 44.6740 83.9694 2505.2134 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Great Britain 52.65 -1.56 108 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Great Britain 52.0141 -0.9640 114.4462 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Great Britain 52.6552 -1.5641 108.0925 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Greenland 76.50 -41.0 469 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Greenland 75.9660 -40.4239 471.9905 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Greenland 76.0305 -40.3902 474.2257 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Indian Ocean -47.6319 99.9677 1940.8913 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Indian Ocean -47.7347 100.0547 1943.3848 GSHHG L1 WGS84 B9-Hillclimbing Barnes (2019)[9]
Madagascar -18.33 46.67 260 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Madagascar -18.3382 46.6663 259.5957 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
Madagascar -18.2645 46.7003 264.0657 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
North America 43.46 -101.97 1639 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
North America 43.3764 -102.0111 1639.6549 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
North America 43.4370 -102.0101 1643.7562 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Pacific Ocean (Point Nemo) -48.89 -123.45 2690 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
Pacific Ocean (Point Nemo) -49.0031 -123.3920 2701.1721 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
Pacific Ocean (Point Nemo) -49.0273 -123.4345 2704.7991 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
South America -14.05 -56.85 1517 GSHHS 1996 Sphere Adaptive Grid Garcia (2007)[1]
South America 1 -14.3902 -56.9922 1490.5321 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]
South America 1 -6.3248 -63.1885 1511.6636 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
South America 2 -10.7342 -59.2126 1467.2206 OpenStreetMap WGS84 B9-Hillclimbing Barnes (2019)[9]
South America 2 -5.0537 -65.5487 1476.4901 GSHHG v2.3.6 (L1) WGS84 B9-Hillclimbing Barnes (2019)[9]

See also

References

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