Open-ocean deep convection is known to occur in a very few locations in the present climate. Convection is important for the ventilation of the oceans, and for the operation of the meridional overturning circulation. Using data from ships and profiling floats, we present evidence for the occurrence of convection in the Irminger Sea of the North Atlantic, south-east of Greenland. Confirmation of this convective site in the North Atlantic will influence our understanding of the connection of the atmosphere to the ocean depths, and of the mechanisms of climate variability.