It's a big shelf of Ice which wasn't supposed to fall apart for another 10 years, but has just started to do so, attributed to climate change, so far as I remember.....
C19A is approximately 2264 square miles in size, that is huge. C19A became the largest iceberg in the world after the previous largest iceberg cracked into two different pieces. The B15 as it was called had held the crown at 4400 square.