Olivia Hislop was waiting for a wave at a beach near the South Island tourist town of Kaikoura on Sunday when she felt a tug on her board.
She turned around, expecting to see a friend fooling around.
Instead, there was a shark half on top of her board and gnashing its teeth, the Marlborough Express newspaper reported.
Hislop tugged her board away from the shark, which promptly turned around, smacking her in the forehead with its tail, and swam off.
"That's when everyone said it was quite a big one because they could see the size of its tail," Hislop was quoted as saying. "I was a bit dazed and everyone was freaking out."
When Hislop paddled out later to catch another wave she said she felt a shark bang against her bare feet, which were dangling in the water off the surf board.
Lifting her foot, she found the shark had bitten through the leash tying the board to her ankle.
"I was expecting to see my toes just dangling," the newspaper quoted her saying, adding that "feeling shocked," she then went and sat on the beach.
She knew of two other surfers "bumped" by sharks at the beach in recent weeks and told the newspaper she would not be braving the same beach any time soon.