There has been a steady rise in search and rescue operations from Belfast Lough's Coastguard station, leading to criticism of ministers' plans to close it.
Figures released in Parliament show there were 50% more callouts to the Bangor centre last year than in 2006 - 650 compared to 460 - with the total rising steadily every year.
Shipping Minister Mike Penning, the key man behind the controversial review of the UK's Coastguard operation, also confirmed that more than a third of the callouts were in the hours of darkness.
The revelation undermines one option put forward by the consultation, which would see the station operate in daylight hours only.
The Government first unveiled plans to operate just three stations around the clock, in Aberdeen, Southampton and Dover, with all others being axed or opening for reduced hours.
Five sub-centres were to open during the day, and one of those will be at either Belfast Lough or Liverpool.
Ministers have since suggested a rethink, and the Government's final decision is expected to be made before the Parliamentary recess on July 19.