An Australian school teacher mauled by a large shark at a Sydney beach says she fired a "left hook" at the predator before it dragged her underwater.

Sydney woman Leah Stewart recounts her harrowing tale of survival on 60 Minutes after losing her arm in a shark attack.

Leah Stewart, 35, spent 10 days in a coma after being viciously mauled in the first shark attack at Sydney's Coogee Beach in over a century on June 13.