A number of kayakers were treated for hypothermia after being airlifted from a "freezing" River Foyle.
The emergency services have been hailed for their work in rescuing 26 people on Saturday.
Five people were airlifted to Derry's Altnagelvin Hospital and 12 were taken by ambulance, according to Foyle Search and Rescue.
Two kayaks capsized on the river between Carrigans in Co Donegal and Magheramason in Co Tyrone at around 2pm.
All of those rescued were aged between 18 and their mid-50s and all were part of the one group with no one suffering from serious injuries, apart from several people suffering the effects of hypothermia.
It is believed they had been participating in a fundraising event for the YMCA.
On Facebook, Foyle Search and Rescue said the incident highlighted the importance of agencies working together.
The rescue operation was a combined effort involving Foyle Search and Rescue, the Irish Coastguard, UK Coastguard, Northern Ireland Fire & Rescue Service, Northern Ireland Ambulance Service, and the PSNI
SDLP MLA for Foyle Mark H Durkan said: "It has been a cold day and the water in the river would have been freezing. Coupled with the strong current and high tide it is extremely fortunate that we did not witness a tragedy here today.
"I must commend the swift and brave actions of Foyle Search and Rescue, the Irish Coast Guard and all the emergency services whose efficiency and professionalism certainly saved lives."
Martin McGuinness tweeted: "Excellent work by Emergency services in their successful efforts to safely recover 26 capsized canoeists today from the River Foyle."
