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We have calculated the spots furthest from the sea in major land masses, also known as Poles of Inaccessibility (PIA), a concept that has raised the interest of explorers. The results are in this table. For the Eurasian pole of inaccessibility (EPIA, located in the figure), the results reveal a misplacement in previous calculations ranging from 156 to 435 km. Though in general there is only one pole for a given coastline, the present calculations show that, within the error inherent to the definition of the coastline, two locations candidate for EPIA, one equidistant from Gulf of Ob, Gulf of Bengal, and Arabian Sea, and the other equidistant from Gulf of Ob, Gulf of Bengal, and Gulf of Bohai, both poles being located in the north westernmost Chinese province of Xinjiang. The distance to the sea at these locations is 2510 and 2514 km respectively, about 120 km closer than popularly thought.


Details in this publication by Garcia-Castellanos & Lombardo, 2007. Source of the C code and Linux scripts to test/reproduce the results are available here.

Introduction 

Distance from the sea is historically related to isolation and inaccessibility. A Pole of Inaccessibility (PIA) is defined as the location furthest from a particular coastline. The concept was first introduced by Vilhjalmur Stefansson (1920) to distinguish between the North Pole and the most difficult-to-reach place in the Arctic. Thereafter, it has been widely used to refer to the place in Antarctica furthest from the sea (e.g., Ramseier, 1966; Lambert, 1971; Bonner, 1987). This exploration challenge was first achieved in 1958 by the 2nd Soviet Antarctic Expedition led by Aleksei Treshnikov (Petrov, 1959). 

The term is also used to refer to the place on Earth that is furthest from any ocean (Eurasian Pole of Inaccessibility, hereafter referred as EPIA), located in central Asia. Explorers such as Cable & French (1944, p. 94) refer to the region of the Dsungarei Desert as “the spot of the globe which is farthest removed from any sea or ocean”. 

In recent years, as expeditions have been conducted to document the PIA of Antarctica (19th Jan. 2007) and Eurasia (Crane & Crane, 1987), there has been an increasing interest in the subject, while academic documentation remains very scarce. Although graphical methods to calculate such poles are long known, as digital coastlines and geographical databases become gradually available, the necessity for a numerical method is growing. 

In this paper, a simple method is proposed and used to calculate the PIA’s associated to the largest landmasses on Earth. The application of this method reveals an error of between 156 and 435 km in the location popularly regarded as the EPIA (Crane & Crane, 1986). 

The Eurasian Pole of Inaccessibility 

Previous (undocumented) calculations of the EPIA did not account for the Gulf of Ob as part of the seas, yielding the location 46°16.8′ N 86°40.2′ E (see Fig. 4; this location is equidistant 2648 km to the Gulf of Baydaratskaya in the Arctic Ocean, the Gulf of Bengal, and the Gulf of Bohai in East China). However, there is no basis to exclude the Gulf of Ob as part of the open sea waters, and all available cartography displays the 10-12 m deep and up to 80-km-wide Gulf of Ob as part of the ocean. Accounting for the Gulf of Ob as part of the Seas, implies a large shift of the EPIA which has two solutions within the uncertainty related to the definition of coastline, as shown in the previous section. 

The two candidate poles found in this paper reduce the Earth’s maximum distance to the coast by more than 130 km, and modify the location of the PIA by 435 km (EPIA1) and 156 km (EPIA2) relative to previous calculations. In the case of EPIA1, also one of the CSP changes from the Gulf of Bohai (East China) to the Arabian Sea. These results question the only documented attempt to explore the EPIA by two explorers in 1986 (Crane & Crane, 1987). 

EPIA1 lies near Kokirqin Shan Mountain (3698 m), at an area of high relief and difficult access at >2000 m above sea level, close to the Chinese borders with Kazakhstan and Kyrgyzstan. EPIA2 lies at 710 m altitude, 174 km NNE of Ürümqi. 

Besides being far from the oceans, both poles are in the largest endorheic basin in the world, meaning there is no fluvial connection to the sea (Cable & French, 1944). This is partially the result of low precipitation values of 200-350 mm/yr as a result of continentality. Both factors have probably enhanced the historical isolation of this region acting as a natural border between the Chinese and the Western civilizations. Its faint presence in history is mostly linked to the relative vicinity (a few hundred km) of the ancient Silk Road. Unsurprisingly, the region is among the less populated areas of the world, and the ethnic group longest rooted in the region, the Uyghur, is linguistically included in the Turkic family and interfingers with population speaking Chinese languages. 

Conclusions 

The location on Earth furthest from the ocean is located in the north-western Chinese province of Xinjiang. Within the uncertainty inherent to the definition of the coastline, two locations are proposed as Pole of Inaccessibility: EPIA1 (44°18'1"N; 81°51'31"E) and EPIA2 (45° 17' 60"N; 88° 8' 24"E). EPIA1 is equidistant 2510 ± 10 km from Gulf of Ob, Gulf of Bengal, and the Arabian Sea, and EPIA2 is equidistant 2514 ± 7 km from Gulf of Ob, Gulf of Bengal, and Gulf of Bohai (China). EPIA1 and EPIA2 are 435 and 156 km far respectively from the location popularly accepted as the EPIA (Fig. 4). 

The spot on planet Earth that is most distant from land (Pole of Inaccessibility of the Pacific Ocean, or Point Nemo) is at 48°52.6′S, 123°23.6′W, 2690 ± 2 km far from the coasts of Motu Nui (Easter Island), Maher Island (Anctartica), and Ducie Island (Pitcairn Islands). PIA’s calculated for other continental masses with the same technique are listed in Table 1. 

References 

  • Bonner, W.N., 1987. Antarctic science and conservation — The historical background. Environment International, 13, 19-25. 
  • Cable, M., & French F. The Gobi Desert; The Macmillan Company, 1944. 
  • Crane, R., & N. Crane, 1987. Journey To The Centre Of The Earth (1987). 
  • Lambert, G., B. Ardouin, E. Brichet and C. Lorius, 1971. Balance of 90Sr over Antarctica: Existence of a protected area. Earth and Planetary Science Letters, 11, 317-323 
  • Petrov, V.P., 1959. Soviet expeditions in Antarctica. The Professional Geographer, 9, 6-10. doi: 10.1111/j.0033-0124.1959.113_6.x 
  • Ramseier, R.O., 1966. Role of sintering in snow construction. Journal of Terramechanics, 3, 1966, 41-50. 
  • Stefansson, V., 1920. The Region of Maximum Inaccessibility in the Arctic. Geographical Review, 10, 167-172. 
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PIA_web_pack.tar.gz
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Daniel Garcia-Castellanos,
Mar 25, 2011, 4:38 AM
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