Dayna McKay, 42, will swim from Prince Rupert harbour to the island community of Lax-Kw'alaams — also known as Port Simpson — at the end of June.
She was first inspired to undertake the swim after her uncle Billy Sampson was diagnosed with prostate cancer in 2009. Last year she made the crossing in the opposite direction.
Sampson is still battling cancer and McKay says her attempt to conquer the ocean is a metaphor for his fight against the disease.
"I know it's a big challenge, and I've never heard of anybody swimming from their village to another city and dedicating it to someone they really care for," she said.
The stretch of cold, rough water is wider than the English Channel or Lake Ontario, but McKay hopes to make the crossing in 19 hours.
"I love being out here. I know what the fishermen feel like on their boats. As soon as they see it nice and calm .… they want to be in their boats. Me, I want to be in the water."
Last year, McKay's swim raised $25,000, and more than 2,000 people turned out to watch her arrive in Prince Rupert.
This year, she's hoping to raise $100,000, and said she'll be focusing on arriving safely in Lax-Kw'alaams.
"I do stop to take in everything. And I just picture coming home and I'm looking forward to that."
McKay took up swimming only a few years ago, after her village built a community pool.