Jim Maya, who runs Maya's Westside Whale Watching on San Juan Island in Washington state, says he was out with a group in Haro Strait when they spotted a humpback whale near D'Arcy Island, in Canadian waters.
"A fairly young female, perhaps five years old, I don't think it was fully grown yet, she just stayed around the boat for an hour swimming underneath the boat, spy-hopping next to us, looking at us," he said.
After they had watched the whale for a short time, the whale disappeared from sight...but then popped back up again right beside the boat.
"We saw its fluke as it went underneath the boat, and of course everyone was thrilled, amazed, a little concerned," said Maya.
Blogger Jeanne Hyde recorded the close encounter on video and later posted it to YouTube.
Maya says the whale, which is nicknamed Wendy, will soon be heading to Hawaii, where humpbacks gather every winter to breed.
Watch the video
D'Arcy Island on Google Maps