ANTARCTICA — All eyes are on the ice as an Antarctic ice shelf that’s thousands of years old is days away from shedding a massive berg.

Business Insider reports that cracks on Antarctica’s Larsen C ice shelf were first noticed in 2010. The rift has grown rapidly since 2016, with only 3 miles of ice keeping the chunk connected to the main shelf.

When it eventually gives way, the resulting iceberg will be one of the largest on record. Using information from CryoSat, the European Space Agency estimates the iceberg to be about 190 meters thick, and containing enough ice to fill 460 million Olympic-sized swimming pools.

The colossal mass of ice won’t raise sea levels when it breaks off, but it might make the rest of the shelf less stable, possibly leading it to disintegrate and collapse into the sea.

If this happens, some scientists believe an ancient glacier currently being held back by the ice shelf could raise sea levels by about 4 inches.

Scientists say icebergs calving from Antarctica isn’t too uncommon, but they’ll be monitoring this one as it drifts from the ice shelf due to it’s large size.