We observe a large simultaneous calving event in Porpoise Bay, East Antarctica, where ~ 2900 km² of ice was removed from floating glacier tongues between January and April 2007. This event was caused by the break-up of the multi-year sea ice usually occupies the bay, which we link to climatic forcing. We also observe a similar large calving event in March 2016 (~ 2200 km²), which we link to the long-term calving cycle of Holmes (West) Glacier.