Pobeda Ice Island was first discovered in 1840. It was seen again in the 1910s, but was gone by the late 1920s. By the 1960s it was back, only to disappear again in the 1970s.
Douglas Mawson, the Australian explorer, arrived off the coast of Antarctica in early 1912. Using charts from an American expedition seventy years earlier, he expected to find an island named “Termination Land.” Instead, he found this:
At 7:40am, February 8, in foggy weather, the ice–cliff of floating shelf–ice was met. This was disposed so as to point in a northwesterly direction and it was late in the day before the ship doubled its northern end. Here the sounding wire ran out for eight hundred and fifty fathoms without reaching bottom. […] A line of large grounded bergs and massive floe–ice was observed ahead trailing away from the ice–wall towards the northwest.The Home of the Blizzard
Mawson concluded that it was an ice tongue, an iceberg that had pushed out from a glacier and into the ocean. But when he returned to the same place nearly twenty years later, he was in for a surprise:
On January 30, as the day progressed, the weather improved, and the ship was steamed back to the south-east with a view to reaching the shelter of Termination Ice Tongue. Great was our surprise however when it was found that no such tongue now existed.The B. A. N. Z. Antarctic Research Expedition, 1929-31
A Soviet research crew found this odd island again in 1960; they dropped a four-person research crew there for a winter and renamed the site Pobeda Ice Island. Because this is what it was: a huge iceberg. The berg had calved off the nearby Denman Glacier (pictured above) and then run aground on some submerged land. This made it, in effect, a temporary island of ice, 70 kilometres wide, locked in the Antarctic sea. But it was temporary; eventually the island would break free and break up, until a new berg calved off the glacier and replaced it.
The upshot of this cycle is that the Pobeda Ice Island only exists for about a decade at a time. Every fifty years or so a new island runs aground at the same location. The most recent Pobeda disappeared about seventeen years ago – but we can expect it to return soon.