The largest iceberg ever reliably recorded is B-15, which broke off Antarctica’s Ross Ice Shelf in March 2000 with a surface area of about 11,000 km² (4,250 sq mi), roughly the size of Jamaica. Second is A-38, about 6,900 km², which calved from the Filchner–Ronne Ice Shelf in October 1998, and third is B-15A, the 6,400 km² main fragment of B-15. Every one of the ten largest on record came from an Antarctic ice shelf, and four of them from the Ross Ice Shelf alone. The table below uses the Wikipedia list of recorded icebergs by area (as of 2026), which compiles figures from NASA, the European Space Agency, the US National Ice Center and contemporary news reports; the sections that follow explain why these particular shelves keep producing giants.
| Rank | Iceberg | Parent ice shelf | Year | Max. area (km²) |
|---|---|---|---|---|
| 1 | B-15 | Ross | 2000 | 11,007 |
| 2 | A-38 | Filchner–Ronne | 1998 | 6,900 |
| 3 | B-15A | Ross (fragment of B-15) | 2002 | 6,400 |
| 4 | A-68 | Larsen C | 2017 | 5,800 |
| 5 | C-19 | Ross | 2002 | 5,500 |
| 6 | B-9 | Ross | 1987 | 5,390 |
| 7 | A-76 | Filchner–Ronne | 2021 | 4,320 |
| 8 | A23a | Filchner–Ronne | 1986 | 4,000 |
| 9 | D-28 | Amery | 2019 | 1,636 |
| 10 | A-81 | Brunt | 2023 | 1,550 |
One caveat before the explanations. Areas are measured from satellite images, often after the berg has already started to shed pieces, so published figures vary: B-15 appears as 10,915 km² in one estimate and 11,007 km² in another, and the timeline in Wikipedia’s Iceberg article adds B-22, about 5,490 km² in 2002, which the list above leaves out. The list also dates A23a to 2021, the year its 4,000 km² was recorded, although the berg itself calved in 1986, which is the year shown in the table here.
Why Every Giant Comes from Antarctica, Not Greenland
The table is all-Antarctic because of the shape of the ice that feeds the ocean. Antarctica is fringed by ice shelves, floating plates of glacier ice hundreds of metres thick that spread out over the sea. When a crack runs right across one, the piece that breaks away is flat-topped and sheer-sided, a tabular iceberg that can be tens or hundreds of kilometres long. Greenland’s glaciers, by contrast, tend to calve irregularly shaped and much smaller icebergs.
The Arctic’s record shows the gap. When the floating tongue of Greenland’s Petermann Glacier lost a piece in August 2010, it was the largest Arctic iceberg to calve since 1962, yet it measured only about 260 km², less than a fortieth of B-15. Even the tallest North Atlantic iceberg on record, sighted by the US Coast Guard icebreaker Eastwind in 1958, stood 168 m above the sea but covered a tiny fraction of the area of an Antarctic tabular berg.
The Ross Ice Shelf: Four of the Top Six, Including B-15
The Ross Ice Shelf is the largest ice shelf in Antarctica, about 500,809 km² in 2013, roughly the size of France, with a seaward ice front more than 600 km long standing 15 to 50 m above the water. Most of it lies within the Ross Dependency claimed by New Zealand. Scientists believe its biggest breakaways, B-15 included, are part of a long-term natural cycle that recurs every 50 to 100 years.
B-15 broke away near Roosevelt Island in the last weeks of March 2000 along cracks that already existed, measuring about 295 km by 37 km. It split up in stages in 2000, 2002 and 2003, and its largest piece, B-15A, was still about 6,400 km². In April 2005 B-15A rammed the Drygalski Ice Tongue and snapped off its tip, then ran aground and broke apart in October 2005, a break-up that ocean swell from a Gulf of Alaska storm, 13,500 km away, may have helped, although a 2010 study blamed mainly the berg’s repeated groundings on the seabed. As late as August 2023 the National Ice Center still tracked one remnant, B-15AB, about 20 km by 7 km.
Two years after B-15, in May 2002, C-19 calved from the Ross Ice Shelf along a fissure scientists had watched since the 1980s, leaving the shelf front roughly where Robert Falcon Scott’s party had mapped it in 1911. By trapping sea ice in the southwestern Ross Sea, C-19 caused a sharp drop in phytoplankton production that season. Earlier still, B-9 broke off in 1987, 154 km long, carrying away the abandoned American base Little America V, which had closed in December 1959; it drifted about 2,000 km over 22 months.
The Filchner–Ronne Shelf and the Weddell Sea: A-38, A-76 and A23a
The Filchner–Ronne Ice Shelf on the Weddell Sea is the second-largest ice shelf on Earth, about 430,000 km², split by Berkner Island into the western Ronne and eastern Filchner sections. It gives three entries to the top 10, and two of them carried research stations away with them.
A-38 calved in October 1998 near Berkner Island, roughly 150 km by 50 km, after stress from the grounded Hemmen Ice Rise opened two inlets that finally met. It took with it Germany’s summer-only Filchner Station. The pieces drifted up the Antarctic Peninsula and grounded east of South Georgia in December 2003, where the remnant A-38B blocked foraging routes and caused deaths among seal and penguin young. A-76, spotted in May 2021 by Keith Makinson of the British Antarctic Survey, was about 170 km long but only 25 km wide, and has been described as shaped like a giant ironing board.
A23a had one of the longest lives of any berg on the list. It broke away in 1986 carrying the Soviet base Druzhnaya I, then stuck fast on the floor of the Weddell Sea for more than three decades. It began moving in 2020, spun for months in 2024 over the Pirie Bank seamount near the South Orkney Islands, and in January 2025, at about 3,500 km², was again the largest iceberg in the world. It grounded off South Georgia in March 2025, broke up after drifting north that September, and formal monitoring ended in March 2026.
The Weddell Sea route explains why so many of these bergs end up near South Georgia. Currents carry them clockwise around the Weddell Gyre, north along the Antarctic Peninsula and out into the Antarctic Circumpolar Current, which runs straight towards the island’s shallow continental shelf.
Larsen C, 2017: How A-68 Cut a Shelf by 12 Percent
The Larsen Ice Shelf runs along the eastern coast of the Antarctic Peninsula and is named after the Norwegian whaling captain Carl Anton Larsen, who sailed along its front in December 1893. Unlike the Ross and Filchner–Ronne, it has been breaking down since the mid-1990s: Larsen B collapsed in 2002, and the shelf as a whole has shrunk from about 85,000 km² to 67,000 km².
A-68 was watched closely for months before it broke. A crack in Larsen C was noticed in November 2016, and in July 2017 a block about 175 km long, 50 km wide and 200 m thick broke free, weighing an estimated one trillion tonnes and covering 5,800 km², larger than the US state of Delaware. The loss reduced Larsen C by 12 percent. The iceberg drifted north towards South Georgia, raising fears in late 2020 that it would ground near penguin and seal colonies, but it shattered instead, and by 16 April 2021 no significant fragments remained.
Amery and Brunt: Smaller Shelves, Smaller Records
The last two places go to shelves that are far smaller than the Ross, and their icebergs are correspondingly modest. D-28 calved from the Amery Ice Shelf in East Antarctica in September 2019, covering 1,636 km² and weighing an estimated 315 billion tonnes. A-81 broke from the Brunt Ice Shelf on 23 January 2023, after a crack called Chasm-1 that had been growing since 2015 finally cut all the way across. It covered about 1,550 km² and broke away only about 20 km from Britain’s Halley Research Station. The current base, Halley VI, opened in 2013 and stands on retractable skis so it can be relocated, and it has been left unstaffed in winter since 2017 over concerns about the spreading cracks. Its predecessor from the same shelf, A-74, had calved in February 2021 at 1,270 km².
Letters A to D: How the US National Ice Center Names Icebergs
The names in the table are not random. The US National Ice Center, the only organisation that names and tracks all Antarctic icebergs, gives a name to any berg more than 10 nautical miles (19 km) long on at least one axis. The letter records the quarter of Antarctica it came from: A for 0° to 90° W (the Bellingshausen and Weddell seas), B for 90° W to 180° (the Amundsen Sea and eastern Ross Sea), C for 90° E to 180° (the western Ross Sea and Wilkes Land) and D for 0° to 90° E (the Amery Ice Shelf and eastern Weddell Sea). The number is a running count, and fragments add a letter, which is how B-15 produced B-15A through B-15AB.
USS Glacier, 1956: a Bigger Iceberg Nobody Can Confirm
There is one bigger claim that no table includes. On 12 November 1956 the US Navy icebreaker USS Glacier reported a tabular iceberg about 335 km long and 97 km wide, larger than Belgium, some 240 km west of Scott Island in the South Pacific. It was recorded before satellite photography, so its estimated dimensions are treated as less reliable, and B-15 keeps the record as the largest iceberg anyone has measured properly. Every one of these bergs began as part of the Antarctic ice sheet, the frozen mass that feeds all of these shelves.