The 19-year-old beauty was holidaying with her family on the Caribbean Island of St Barts when she was spotted wearing a helmet and life jacket whilst jumping and balancing above the water on a 'Back to the Future' style water-craft.<br />The Chanel model was joined by her 18-year-old sister Kylie Jenner and the teen's boyfriend Tyga, 25, however pregnant Kim Kardashian West stayed cooped up inside the yacht.
