The mega iceberg A-68A, which started out four times the size of Greater London, calved off the Larsen Ice Shelf on the Antarctic Peninsula in 2017. Scientists tracked the iceberg on its 4000 km journey across the South Ocean until it reached the sub-Antarctic island of South Georgia, where it broke up and melted over a three-month period from late 2020 to February 2021.

The results are published in the journal Progress in Oceanography.

In February 2021, a team from British Antarctic Survey (BAS) and National Oceanography Centre (NOC) diverted a research ship already in the area to record how the iceberg's melting was contributing to the ocean and ecosystem of South Georgia.

The occurrence of icebergs at South Georgia is common, and shipping reports have historically recorded their prevalence in the region between the Weddell Sea and northern Scotia Sea and leading onwards to South Georgia.

The route is known as "iceberg alley" as icebergs that calve off Antarctica typically drift northwards, carried by ocean currents to the warmer open ocean. However, very few of these icebergs have been studied by scientific expeditions, which are planned years in advance and focus on specific studies rather than opportunistic science.