Largest iceberg (current)

The largest current iceberg is A23A, which was measured based on satellite imagery at 40 x 32 nautical miles (74 x 59 km) in February 2024, with an area of approximately 3,900 km^{2 (1,505 sq mi)}, which is twice the size of Greater London, UK. A23A is an unusually long-lived iceberg, having detached from the Filchner Ice Shelf in August 1986 but soon getting stuck on the sea-floor of the Weddell Sea. However, after almost 30 years in the same position, it began to move in earnest in early 2022 and, by November 2023, it had reached the northern tip of the Antarctic Peninsula. It will continue its speedy journey northwards along "iceberg alley" into much warmer, iceberg-destroying waters of the South Atlantic, where it will soon lose its world record status.

The largest iceberg ever was in excess of 31,000 km2 (12,000 sq mi). It was 335 km long and 97 km wide (208 x 60 mi) – larger than Belgium – and was sighted 240 km (150 mi) west of Scott Island, in the Southern Ocean by the USS Glacier on 12 November 1956. The extent of the iceberg witnessed by the crew of the USS Glacier was estimated, as they did not have the benefit of satellite photography.

The largest iceberg reliably assessed using satellite imagery is B15, which calved from Antarctica's Ross Ice Shelf in March 2000 and, according to NASA, measured approximately 300 km long by 40 km wide (186 x 25 mi), with a surface area of 11,000 km2 (4,250 sq mi).