John Hartman is a South African shark expert . Today he travels with tours teaching his shark knowledge to tourists . `` I became the guy -- if you want to film sharks , go to Andre . For decades he swam with great white sharks until a stroke left him unable to swim .
John Hartman is a South African shark expert . Today he travels with tours teaching his shark knowledge to tourists . For decades he swam with great white sharks until a stroke left him unable to swim .