In geography, a pole of inaccessibility represents the most remote and challenging location to reach within a specific landmass, sea, or topographical area based on a particular criterion. This concept denotes a spot that is exceptionally difficult to access according to the chosen criterion. Often, it refers to the point furthest from the coastline, indicating the deepest point within a landmass from the shore (continentality), or the most distant point in the ocean from any landmass (oceanity). Essentially, a pole of inaccessibility can be described as the center of the largest circle that can be drawn within a specified area without touching the coast. The pole’s location will also be uncertain when the coastline is not clearly defined.
Northern Pole of Inaccessibility
The Northern Pole of Inaccessibility, often referred to as the Arctic Pole, is located in the Arctic Ocean on pack ice, at the furthest point from any landmass. Initially, this position was incorrectly thought to be at 84°3′N 174°51′W. The origin of this definition is unclear, but it is speculated that Sir Hubert Wilkins might have identified it while planning his 1927 attempt to fly across the Arctic Ocean, which he completed in 1928. In 1968, Sir Wally Herbert nearly reached this point by dogsled but was thwarted by shifting sea ice, as recounted in his book “Across the Roof of the World.” In 1986, a Soviet expedition led by Dmitry Shparo claimed to reach the original location on foot during the polar night.
In 2005, explorer Jim McNeill sought to redefine the pole’s position using modern GPS and satellite technology, collaborating with scientists from the National Snow and Ice Data Center and the Scott Polar Research Institute. Their findings, published in the Polar Record by Cambridge University Press in 2013, established a new position at 85°48′N 176°9′W. This location is 1,008 km (626 miles) from the three nearest landmasses: Henrietta Island in the De Long Islands, Arctic Cape on Severnaya Zemlya, and Ellesmere Island, and it is over 200 km from the previously accepted position.
Due to the constant movement of the pack ice, no permanent structure can exist at this pole. As of February 2021, McNeill reported that, to the best of his knowledge, no one had reached the new position of the Northern Pole of Inaccessibility, particularly not from the last landfall across the ocean’s surface. This location remains an important target for scientific exploration.
Southern Pole of Inaccessibility
The Southern Pole of Inaccessibility is the point on the Antarctic continent that is furthest from the Southern Ocean. Various coordinates have been proposed for this pole due to differing methods of measuring the “coastline,” whether by the grounding line or the edges of ice shelves, and due to the challenges of pinpointing the solid coastline, ice sheet movements, and advancements in survey data accuracy. Typographical errors have also contributed to these discrepancies.
The location most commonly associated with the Southern Pole of Inaccessibility is the site of a Soviet research station at 82°6′S 54°58′E (though some sources list it as 83°6′S 54°58′E). This site is 1,301 km (808 mi) from the South Pole and sits at an elevation of 3,718 m (12,198 ft). The Scott Polar Research Institute, using different criteria, places the pole at 85°50′S 65°47′E.
Recent studies by Rees et al. (2021), using adaptive gridding and B9-Hillclimbing methods, identified two poles of inaccessibility for Antarctica: an “outer” pole at the edge of floating ice shelves and an “inner” pole at the grounding lines. They located the outer pole at 83.904°S 64.890°E, 1,590.4 km (988.2 mi) from the ocean, and the inner pole at 83.610°S 53.720°E, 1,179.4 km (732.8 mi) from the grounding lines.
Reaching the Southern Pole of Inaccessibility is significantly more challenging than reaching the geographic South Pole. On December 14, 1958, the 3rd Soviet Antarctic Expedition, led by Yevgeny Tolstikov, established the temporary Pole of Inaccessibility Station at 82°6′S 54°58′E during the International Geophysical Year. A second Soviet team returned in 1967. Today, a building remains at this site, marked by a bust of Vladimir Lenin facing Moscow, which is protected as a historical site.
On December 11, 2005, members of the Spanish Transantarctic Expedition, Ramón Hernando de Larramendi, Juan Manuel Viu, and Ignacio Oficialdegui, became the first to reach the southern pole of inaccessibility at 82°53′14″S 55°4′30″E, a location updated by the British Antarctic Survey. The team continued to the second southern pole of inaccessibility, accounting for ice shelves and continental land, reaching it on December 14, 2005, at 83°50′37″S 65°43′30″E. This expedition covered over 4,500 km (2,800 mi) and achieved the fastest polar journey without mechanical aid, averaging around 90 km (56 mi) per day, with a maximum of 311 km (193 mi) per day using kites for propulsion.
On December 4, 2006, Team N2i, consisting of Henry Cookson, Rupert Longsdon, Rory Sweet, and Paul Landry, embarked on an expedition to reach the historical pole of inaccessibility without mechanical assistance, using traditional man-hauling and kite-skiing. They reached the abandoned Soviet station on January 19, 2007, rediscovering the Lenin statue. Only the bust was visible, with the rest buried under snow. The team was retrieved by plane from the Vostok base and returned to Cape Town on the Russian polar research vessel Akademik Fyodorov.
On December 27, 2011, Sebastian Copeland and Eric McNair-Laundry reached the 82°6′S 54°58′E pole without resupply or mechanical support. Departing from Novolazarevskaya Station, they completed the first East-West crossing of Antarctica through both poles, covering over 4,000 km (2,500 mi).
Due to technological advancements and debates over the continental edge’s position, the exact location of the pole of inaccessibility may vary. However, for sports expeditions, the Soviet station’s fixed point is often used, as recognized by Guinness World Records for Team N2i’s 2006-2007 expedition.
Oceanic Pole of Inaccessibility
The Oceanic Pole of Inaccessibility, also known as Point Nemo, is located at approximately 48°52.6′S 123°23.6′W. This point in the ocean is the furthest from any landmass, representing the solution to the “longest swim” problem. If someone were to fall overboard at this location, they would be as far from land as possible in any direction. Point Nemo is situated in the South Pacific Ocean and is equidistant—about 2,688 km (1,670 mi)—from three land vertices: Pandora Islet of the Ducie Island atoll (part of the Pitcairn Islands) to the north, Motu Nui (near Easter Island) to the northeast, and Maher Island (near Siple Island off the coast of Marie Byrd Land, Antarctica) to the south. The precise coordinates of Point Nemo depend on the exact coordinates of these three islands, as the “longest swim” problem dictates that the ocean point is equally distant from each of them.
This region is so remote that, at times, the nearest humans are astronauts aboard the International Space Station when it passes overhead, as it is more than 400 kilometers (250 mi) from any inhabited area.
The antipode of Point Nemo—the point directly opposite on the Earth’s surface—is located at roughly 48°52.6′N 56°36.4′E in the Aktobe region of western Kazakhstan, about 50 km (30 miles) SSE of the town of Shubarkuduk.
Point Nemo is relatively lifeless due to its location within the South Pacific Gyre, which blocks the influx of nutrients, and its distance from land means it receives minimal nutrient runoff from coastal waters.
Additionally, the South Pacific Ocean west of Point Nemo is home to the geographic center of the water hemisphere at 47°24′42″S 177°22′45″E, near New Zealand’s Bounty Islands. The geographic center of the Pacific Ocean is located further northwest, where the Line Islands begin, west of Starbuck Island at 4°58′S 158°45′W.
History
Point Nemo was first identified by Croatian survey engineer Hrvoje Lukatela in 1992. In 2022, Lukatela recalculated the coordinates of Point Nemo using data from OpenStreetMap and Google Maps to compare those results with his original calculations, which were based on the Digital Chart of the World.
The Point and its surrounding areas have garnered significant literary and cultural attention, earning the name Point Nemo—a nod to Jules Verne’s Captain Nemo from the novel 20,000 Leagues Under the Sea. Lukatela named it after Captain Nemo, as the novel was a favorite from his childhood. Additionally, the general area features prominently in H.P. Lovecraft’s 1928 short story “The Call of Cthulhu” as the location of the fictional city of R’lyeh, despite the story being written 66 years before Point Nemo was identified.
The broader region is also known as a “spacecraft cemetery.” Hundreds of decommissioned satellites, space stations, and other spacecraft are directed to re-enter the atmosphere and fall there to minimize the risk of impacting inhabited areas or maritime traffic. The International Space Station (ISS) is scheduled to crash into Point Nemo in 2031.
Continental Poles of Inaccessibility
Eurasia
The Eurasian Pole of Inaccessibility (EPIA) is located in northwestern China, near the Kazakhstan border. This point is the furthest possible location on land from any ocean, given that Eurasia, and even just Asia alone, is the largest continent on Earth.
Earlier calculations indicated that the EPIA is 2,645 km (1,644 mi) from the nearest coastline, positioned at 46°17′N 86°40′E, roughly 320 km (200 mi) north of Ürümqi in the Xinjiang Autonomous Region of China, within the Gurbantünggüt Desert. The closest settlements to this point are Hoxtolgay Town (46°34′N 85°58′E), about 50 km (31 mi) northwest; Xazgat Township (夏孜盖乡; pinyin: Xiàzīgài xiāng) (46°20′N 86°22′E), about 20 km (12 mi) west; and Suluk (46°15′N 86°50′E), about 10 km (6.2 mi) east.
However, this location disregards the Gulf of Ob as part of the ocean. A 2007 study proposed two alternate locations as the farthest points from any ocean (considering the uncertainty in coastline definitions): EPIA1 at 44.29°N 82.19°E and EPIA2 at 45.28°N 88.14°E, situated 2,510±10 km (1,560±6 mi) and 2,514±7 km (1,562±4 mi) from the oceans, respectively. These points form a close triangle around the Dzungarian Gate, a historic migration route between East and West. EPIA2 is near the settlement called K̂as K̂îr Su in a region named K̂îzîlk̂um (قىزىلقۇم) in Karamgay Township, Burultokay County.
Elsewhere in Xinjiang, the location 43°40′52″N 87°19′52″E in the southwestern suburbs of Ürümqi (Ürümqi County) was designated as the “center point of Asia” by local geography experts in 1992, and a monument was erected there in the 1990s, making it a local tourist attraction.
Interestingly, the radii of the continental and oceanic poles of inaccessibility are similar; the Eurasian poles EPIA1 and EPIA2 are about 178 km (111 mi) closer to the ocean than the Oceanic Pole of Inaccessibility is to land.
Africa
In Africa, the pole of inaccessibility is located at 5.65°N 26.17°E, making it 1,814 km (1,127 mi) from the nearest coastline. This point is situated near the town of Obo in the Central African Republic, close to the tripoint where the borders of South Sudan, the Democratic Republic of the Congo, and the Central African Republic converge.
North America
In North America, the continental pole of inaccessibility is located on the Pine Ridge Reservation in southwest South Dakota, approximately 11 km (7 mi) north of the town of Allen. This point is 1,650 km (1,030 mi) from the nearest coastline, at coordinates 43.36°N 101.97°W. In 2021, a marker was placed at this location, symbolizing the seven Lakota Values and the four colors of the Lakota Medicine Wheel.
South America
In South America, the continental pole of inaccessibility is located in Brazil at 14.05°S 56.85°W, near Arenápolis in Mato Grosso, and is 1,504 km (935 mi) from the nearest coastline. In 2017, the Turner Twins became the first adventurers to trek to this South American Pole of Inaccessibility. In 2019, it was discovered that there is a second South American Pole of Inaccessibility to the north, with its position varying significantly depending on the coastline datasets used.
Australia
In Australia, the continental pole of inaccessibility is situated at 23.17°S 132.27°E, approximately 920 km (570 mi) from the nearest coastline. This point is located roughly 161 km (100 miles) west-northwest of Alice Springs. The closest town to this location is Papunya, located in the Northern Territory, about 30 km (19 mi) southwest of both the pole of inaccessibility and Alice Springs.
Methods of Calculation
Various factors influence the calculation of geographic poles of inaccessibility using computer modeling methods, as outlined below:
Poles are computed based on specific coastline datasets. Currently utilized datasets include the GSHHG (Global Self-consistent, Hierarchical, High-resolution Geography Database) and OpenStreetMap (OSM) planet dumps. GSHHG claims 500-meter precision for 90% of identifiable coastal features, while OSM, being volunteer-built, lacks such guarantees but is generally considered to have high accuracy characteristics.
A distance function is crucial for determining distances between coastlines and potential poles. Traditional approaches involve projecting data onto planes or conducting spherical calculations. Recent advancements employ different algorithms and high-performance computing techniques, utilizing ellipsoidal calculations.
Optimization algorithms play a critical role in refining pole locations. The 2007 adaptive grid method by Garcia-Castellanos and Lombardo is widely used, involving the creation of a rectangular grid (e.g., 21×21 points). Each point’s distance from the coastline is calculated, and the farthest point is identified. The grid is then recentered on this point and iteratively shrunk, typically achieving high precision (e.g., 100-meter level), though it may converge to a local minimum.
A newer method, B9-Hillclimbing by Barnes (2019), employs a polyhedron in 3D space. Initial points are evenly spaced by 100 kilometers and subjected to numerical optimization techniques like hill climbing or simulated annealing to maximize the distance to the coastline. This method uses a 3D Cartesian point cloud to accelerate computations. Recent studies, such as Rees (2021), demonstrate agreement between these methods at the meter level.
To date, there has been no comprehensive meta-study encompassing all methodologies and datasets used. However, successive studies have compared their results with previous calculations, claiming advancements. For instance, the Garcia-Castellanos and Lombardo method revealed significant errors in traditional calculations, such as the Eurasian Pole of Inaccessibility reported by Crane & Crane (1987). Rees improved the Arctic Pole of Inaccessibility by over 200 kilometers using similar methods. Barnes’ refinement of the South American Pole of Inaccessibility corrected a 57-kilometer error attributed to inaccurate coastline data, demonstrating ongoing improvements in accuracy and methodology.
