An Irish Coast Guard spokesman said the woman was caught in strong tides at the mouth of Lough Foyle.
Greencastle Coast Guard teams responded to the emergency with the Foyle Ferry also assisting.
The volunteers were able to bring the woman to shore where she was met by relieved members of her family who had helped to raise the alarm.
Meanwhile the Sligo Rescue 118 helicopter was scrambled to north Donegal after three people were cut off by the tide near Ards Friary.
Volunteers from the Mulroy Coast Guard also went to the area – but the three people were able to make their way ashore.
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