Big Diomede or Ratmanov Island (Chuk. Imelin, Inuit. Imaqliq) is
an island in the Diomede Islands in the Bering Strait, the most
eastern point of the territory of the Russian Federation.
Administratively it belongs to the Chukotka region of the Chukotka
Autonomous Okrug. There is no permanent population on the island;
the base of the Russian border guards is located here.
Named after the
Russian navigator M.I.Ratmanov.
Big Diomede Island, also known as Ratmanov Island (Russian: Остров
Ратманова; Chukot: Имэлин; Inupiaq: Imaqłiq), is a remote, uninhabited
rocky island in the Bering Strait, forming the westernmost of the two
Diomede Islands. It represents Russia's easternmost point and lies just
across the international border from the United States, highlighting its
unique geopolitical and geographical significance. The island is part of
the Chukotsky District in the Chukotka Autonomous Okrug, emphasizing its
position in the harsh Arctic environment of Far Eastern Russia.
Location and Coordinates
Situated in the middle of the Bering Strait,
Big Diomede is approximately 45 kilometers (28 miles) southeast of Cape
Dezhnev on the Chukchi Peninsula in Siberia. Its coordinates are
65°46′52″N 169°03′25″W, placing it west of the International Date Line
(which runs about 1.3 kilometers east of the island) but in the western
hemisphere by longitude. The island is separated from its smaller
counterpart, Little Diomede (part of Alaska, USA), by a narrow strait
measuring about 3.8 kilometers (2.4 miles) at its closest point—this
strait not only marks the U.S.-Russia border but also coincides roughly
with the International Date Line, creating a 21-hour time difference
between the two islands. Big Diomede is roughly 35.68 kilometers from
the Chukotka coast and about 40 kilometers from mainland Alaska, making
it closer to the U.S. continent than to Russia's. The surrounding Bering
Strait averages 30 to 50 meters in depth and spans about 85 kilometers
at its narrowest, with numerous smaller islands like Fairway Rock
nearby.
Physical Dimensions and Size
Big Diomede covers an
area of approximately 29 square kilometers (11 square miles), making it
significantly larger than Little Diomede (about 7.5 square kilometers).
(Note: Some sources cite a smaller area of 10 square kilometers, but
more detailed geographic assessments align with the larger figure.) The
island stretches 8.7 kilometers from north to south and 4.7 kilometers
from east to west, giving it an elongated, roughly rectangular shape.
Depths off its coast reach up to 43 meters, contributing to the
challenging maritime environment around it.
Terrain and
Topography
The island's terrain is characterized as a rocky tuya-type
formation—a flat-topped volcanic structure formed under glacial ice
during the Pleistocene era, resulting in steep cliffs and rugged
surfaces. Its coastline consists primarily of boulders and rocky
outcrops, with only narrow strips of coastal beach in places. The
northern coast is relatively gentle compared to the steeper southern
areas, where the southernmost point is Cape Yuzhny. Key capes include
Cape Horseman at the extreme north and Cape Skalisty to the east.
Several small rivers traverse the island: two flow northward from the
central region, while one descends southeastward from the highest peak.
The landscape is wind-lashed and barren, typical of Arctic volcanic
outcrops, with no significant forests or valleys. The highest point,
Mount Krysha (also called Roof), rises to 505 meters (1,657 feet)
slightly south of the island's geographic center, dominating the
topography and offering a stark, elevated plateau.
Climate
Big
Diomede experiences a severe polar climate, influenced by its Arctic
location in the Bering Strait. Winters are long, extremely cold, and
dark, with temperatures often dropping below -20°C (-4°F), exacerbated
by strong winds and frequent blizzards. Summers are short and cool,
rarely exceeding 5–10°C (41–50°F), with persistent fog, overcast skies,
and occasional rain or snow. The strait frequently freezes over in
winter, forming sea ice that connects the islands temporarily, while
summer brings open water interspersed with ice floes. A weather station
on the north coast monitors these conditions, recording high humidity,
low precipitation (mostly as snow), and wind speeds that can exceed 100
km/h (62 mph) during storms. Climate change has impacted the region,
with reduced sea ice duration affecting local ecosystems.
Flora
and Fauna
Vegetation on Big Diomede is sparse and typical of Arctic
tundra, consisting mainly of mosses, lichens, low-growing shrubs, and
hardy grasses adapted to the short growing season and permafrost soils.
No trees or significant plant diversity exist due to the extreme
conditions. The island is richer in fauna, particularly as a vital
seabird habitat. It has been designated an Important Bird Area (IBA) by
BirdLife International, hosting colonies of at least 11 species,
including horned puffins, tufted puffins, guillemots, parakeet auklets,
least auklets, and crested auklets. Rare sightings, such as a rufous
hummingbird in 1976, suggest occasional vagrant species. Marine life
thrives in the surrounding waters: pinnipeds like ringed seals, bearded
seals, and walruses haul out on shores or ice, while cetaceans including
gray whales (common) and bowhead whales (rarer) migrate through the
strait. The nutrient-rich Bering Sea supports these populations, making
the area ecologically significant despite its isolation.
Geological Features
As a tuya-type island, Big Diomede originated
from subglacial volcanic eruptions, resulting in its flat-topped,
steep-sided profile composed of basaltic rock layers. Erosion from wind,
waves, and ice has sculpted the rugged cliffs and boulder-strewn coasts.
The island lacks active volcanism but shares the Bering Strait's
tectonic activity, part of the boundary between the North American and
Eurasian plates. Permafrost underlies much of the surface, influencing
soil stability and hydrology.
Human Presence and Other Aspects
Though uninhabited by civilians, Big Diomede hosts a Russian military
base midway along the north shore, a border guard post, and a polar
research station, along with infrastructure like a helipad. These
facilities underscore its strategic role in border monitoring. Access is
restricted, primarily by sea or air in summer, with winter ice
potentially allowing foot travel (though prohibited). The island's
isolation and harsh geography make it a symbol of the Arctic's extremes,
where natural forces dominate human influence.
Prehistory and Indigenous Habitation
Big Diomede Island, also
known as Ratmanov Island in Russian nomenclature, is the larger of the
two Diomede Islands located in the Bering Strait, approximately 2.4
miles (3.8 kilometers) west of its smaller counterpart, Little Diomede.
The island spans about 29 square kilometers and features rugged terrain
with steep cliffs and a highest point of around 1,200 feet (366 meters).
Archaeological evidence suggests that the Diomede Islands have been
inhabited for thousands of years by indigenous Arctic peoples, primarily
the Inupiaq (also referred to as Yupik or Eskimo in historical
contexts). These communities relied on hunting marine mammals like
seals, walruses, and whales, as well as fishing and gathering, adapting
to the harsh subarctic environment.
The first documented European
reference to indigenous inhabitants on islands in the Bering Strait
comes from the Russian explorer Semyon Dezhnev in 1648. During his
expedition, Dezhnev reported encountering two islands populated by
natives who wore bone lip ornaments, a traditional adornment among
Chukchi and Inuit peoples. While it's uncertain if these were precisely
the Diomede Islands, this account highlights the long-standing human
presence in the region. The indigenous population on Big Diomede lived
in small, semi-permanent settlements, engaging in trade and cultural
exchanges with communities on the Siberian mainland and Alaska. These
groups navigated the treacherous waters of the strait using skin boats
(umiaks) and maintained a nomadic lifestyle influenced by seasonal
migrations of wildlife.
European Exploration and Naming
European awareness of the Diomede Islands began in the early 18th
century amid Russian efforts to explore and map the North Pacific. In
1728, the Danish navigator Vitus Bering, sailing under Russian
commission, sighted the islands on August 16 (Old Style calendar; August
26 New Style). This date coincided with the feast day of Saint Diomedes
in the Russian Orthodox Church, prompting Bering to name the islands
after the saint. Bering's expedition was part of a broader imperial push
by Peter the Great to determine if Asia and North America were
connected, and his voyage through the strait (later named after him)
confirmed their separation.
Further mapping occurred in 1732 when
Russian geodesist Mikhail Gvozdev accurately determined the longitude
and latitude of the two islands during his survey of the region. These
early explorations laid the groundwork for Russian claims in the area,
though the islands remained largely peripheral to colonial activities
until the mid-19th century. The indigenous inhabitants continued their
traditional ways, occasionally interacting with passing explorers or
whalers, but the islands' remote location shielded them from significant
outside interference during this period.
The 1867 Border Division
and the Alaska Purchase
A pivotal moment in Big Diomede's history
came with the Alaska Purchase in 1867, when Russia sold its North
American territories to the United States for $7.2 million. The treaty
explicitly defined the new international border, which passed through
the Bering Strait and separated the Diomede Islands "equidistantly"
between Krusenstern Island (Little Diomede, or Ignaluk) and Ratmanov
Island (Big Diomede, or Nunarbuk). This division placed Big Diomede
under continued Russian sovereignty while Little Diomede became part of
the U.S. The border's placement was strategic, following the 168th
meridian west and aligning with the International Date Line, which runs
between the islands.
At the time, the indigenous population on Big
Diomede found themselves bisected by an arbitrary line, leading to
unique social and familial challenges. Families and clans that had
intermarried across the islands were now divided by empires, though
informal crossings continued for a time due to the lack of enforcement.
The sale of Alaska marked the beginning of the islands' role as a
geopolitical curiosity, symbolizing the proximity of two vast
nations—Russia and the U.S.—separated by just a narrow strait that
freezes in winter, sometimes allowing foot travel.
20th Century:
World Wars and the Cold War Era
The early 20th century saw limited
development on Big Diomede, with the island remaining sparsely populated
by indigenous communities. However, the onset of World War II and the
subsequent Cold War transformed it into a strategic outpost. During
World War II, the Bering Strait's location made the islands potential
points for monitoring Japanese or Axis activities, though no major
conflicts occurred there.
The Cold War escalated tensions
dramatically. In 1948, as hostilities between the Soviet Union and the
West intensified, the Soviet government forcibly relocated Big Diomede's
entire indigenous population—estimated at a few dozen families—to the
Chukotka mainland in Siberia. This move was part of a broader policy to
secure border regions and prevent espionage or defections. In their
place, the Soviets established a military base on the island, complete
with radar installations, border guard posts, and defensive structures.
The strait between the islands became known as the "Ice Curtain,"
analogous to the Iron Curtain in Europe, symbolizing the ideological
divide. Crossings were strictly prohibited, and the islands served as a
stark reminder of superpower rivalry.
The military presence
persisted throughout the Cold War, with Big Diomede hosting Soviet (and
later Russian) border troops. A notable event occurred in 1987 when
American swimmer Lynne Cox completed a historic 2.7-mile (4.3-kilometer)
swim from Little Diomede to Big Diomede in frigid waters, taking about
two hours. Her feat was hailed as a gesture of goodwill, earning
congratulations from both Soviet leader Mikhail Gorbachev and U.S.
President Ronald Reagan, and it briefly thawed relations amid
perestroika.
Post-Cold War Developments and Current Status
With the dissolution of the Soviet Union in 1991, the "Ice Curtain"
softened, but Big Diomede retained its military significance. The island
has no permanent civilian population today, with only rotating Russian
border guard units stationed there. As of January 2023, official
population figures list it at 0 residents, though temporary military
personnel are present. The International Date Line's placement means Big
Diomede is often called "Tomorrow Island," being 21 hours ahead of
Little Diomede (20 hours during daylight saving time), creating a time
paradox where one can theoretically "see the future" from the American
side.
In the post-Cold War era, the island has featured in cultural
and exploratory narratives. For instance, in 1995, British adventurer
Michael Palin attempted to include the Diomedes in his BBC documentary
series Full Circle, starting on Little Diomede but unable to reach Big
Diomede due to weather. Environmental changes, such as reduced sea ice
from climate change, have impacted the region, potentially easing winter
crossings but raising concerns about ecological stability and indigenous
rights. Discussions about repatriating descendants of the relocated
inhabitants or establishing joint U.S.-Russian scientific outposts have
surfaced sporadically, but no major changes have occurred as of 2025.
Big Diomede remains a symbol of geopolitical boundaries, environmental
fragility, and human resilience in one of the world's most remote
locales.