The eyewitness who raised the alarm after 26 canoeists fell into the River Foyle has said he is amazed they all made it out alive.
Ian Faulkner, whose house overlooks the river at Magheramason, watched the weekend emergency unfold through his telescope with his wife Diane.
He believes a tragedy was narrowly averted, as he has never seen the water so rough.
Two canoes capsized at around 2pm on Saturday during a fundraising event for the YMCA.
There was a heavy swell in windy conditions and both canoes began to take in water on the river between Magheramason in Co Tyrone and Carrigans in Co Donegal.
The PSNI, Foyle Search and Rescue, Coleraine Coastguard, and the Fire and Rescue Service were among those involved in the rescue, which was declared a major incident.
Six people were airlifted to Londonderry's Altnagelvin Hospital and treated for mild hypothermia. Another 12 were taken by ambulance and the rest were treated at the scene. Mr Faulkner said: "I have a great view over the River Foyle and it happened directly across from my house.
"I came home from work and noticed the water was very, very rough.
"I looked out my window and thought I could see a canoe. I have a telescope and also looked through this.
"I said to my wife, 'That boat is going to capsize'. The swell was so big. Two minutes later I noticed another canoe coming around the corner. I went to boil the kettle and when I came back I could not see it but I saw a lot of people in the water. I said to my wife to phone 999 right away.
"The people were in the water a good half-hour to 40 minutes."
Mr Faulkner first noticed a helicopter at the scene, then Foyle Search and Rescue. He said it was a worrying wait as he and his wife watched those in the water being separated from each other.
"The swells were so big we were losing sight of them," he said. "There was a strong current at the time. I am surprised everyone got out alive.
"We have only been here nine or 10 years but I have never seen the water so rough.
"I couldn't believe there were canoes in the river that day."
John McPoland of the NI Ambulance Service said emergency services sprang into action quickly.
"What we've found is that our capacity to respond to such an incident was severely tested for all emergency services and it's a tribute to all the services involved that they were able to pull together so quickly and ensure there was no tragedies involved in the incident," he said.