As the narrow window for attempting the challenging swim from Northern Ireland to Scotland opened last week, only one of three first individuals to attempt it was successful.
San Francisco native Catherine Breed, 26, finished in a time of just over 11 hours.
She set off from Donaghadee at 3.57am on Tuesday, and reached the Scottish coastline close to Portpatrick at around 3pm.
Two others who attempted the marathon swim last week were forced to turn back due to the challenging conditions, including the cold waters of around 11 degrees, strong currents and large numbers of jellyfish.
Ms Breed told PA that she had aimed to break the current record of 9 hours, 35 minutes,
However, inclement conditions turned the record attempt into a fight to finish.
She said: "The plan was to go for three hours and then re-evaluate because we thought it was going to get better, so we went for three hours and
Padraig said I think it's going to get better, you just have to fight for it - the record.
"Then after a couple of hours of it not getting better, I realised I was going to have to fight to finish it."
M Breed said she counted 150 Lion's Mane jellyfish across her swim.
She added: "Everyone told me there's no jellyfish in the channel right now because it's so cold, but within 15 minutes I saw three of them below me, and
I panicked a little.
"I counted 150 Lion's Mane, but I only got stung once. I think that was because I wasn't paying attention and put my arm through it's tentacles, but it didn't hurt much."
Ms Breed said she is determined to return to break the record.
"I trained so hard for a long time for this and I went into it hoping to get a record, but knowing it wasn't guaranteed," she said.
"After doing the channel I feel like I could do it in the right conditions. I don't want to just leave it sitting."
Ms Breed said she has been swimming since the age of four, and grew into a competitive high school swimmer before winning a scholarship to UC Berkeley and making it to Olympic team US trials.
"When I graduated I didn't want to give up swimming, but I didn't want to race in the pool anymore, so I joined an open water swim team in Sam Francisco," she said.
"People told me I should start setting goals so I did Lake Tahoe and then I did the English Channel, and then stumbled on to this one.
"Although I always said I would never do it, when I heard about it, I thought who on earth would want to swim for that many hours in freezing water with jellyfish."
The North Channel swim has become more popular since its inclusion in the Oceans Seven challenge.
That includes swims across the English Channel, the Cook Strait in New Zealand, the Molokai Channel in Hawaii, Catalina Channel in California, Tsugaru Strait in Japan and the Strait of Gibraltar.
But the North Channel swim can only be attempted during the summer months when the sea is warmer, during neap tides and calm weather.
Padraig Mallon, of Infinity Channel Swimming - who guided Ms Breed, said more than 60 people are set to attempt the North Channel this year, with him and two other skippers.
"It's the biggest year so far, last year there were 27 attempts," he said.
"As well as the North Channel, I'll be piloting swims from the Isle of Man to Ireland, Wales to Ireland and the Dal Riata Channel from the Mull of Kintyre to Ireland.
"These swims are among the toughest in the world and we are seeing people coming from all over the world to attempt them.
"In most sports there is a prevalence of men, but in channel swimming, there is a prevalence of women, females can put up with that pain and mental challenge more than the male channel swimmers can do."