David Sheridan was riding his board at Valla Beach on the northern coast of New South Wales state on Oct. 26 when he noticed a large shadow in the water in front of him.
"At first I thought it was the shadow from my kite. But I quickly realized it was a whale," said Sheridan, a 42-year-old high school teacher. He commented to The Associated Press by e-mail.
"The whale kept coming up. ... I did not know what to expect and I went over its back just past its fin," he said. "Next thing I felt was its tail come up and hit me on the back of the head."
At first, Sheridan feared the whale's strike could knock him out or worse.
"Soon after the initial impact the tremendous force subsided and I kite-surfed away with my legs shaking, hooting and yelling filled with excitement and relief," he said.
Southern Right and other types of whales are common in waters off Australia's east coast at this time of year as they migrate north from the Antarctic Ocean with their young.
"It's unfortunate that my mates weren't close enough to witness the action, and I don't think they really believed my story at the time," he said.