This study examined the plasticity of life history traits, fecundity, reproductive potential and nesting success or Flatback sea turtles (Natator depressus) at West Alligator Head and Field Island, Kakadu National Park, Northern Territory, Australia. Beaches in the area were assessed to their suitability as successful nesting locations. Comparisons were based on the physical properties or the sand, the nature of the coastal vegetation and the seaward approaches to the beaches. Predation of eggs and mortality of hatchlings at each beach were monitored throughout two nesting seasons to identify the major influence on hatchling survivorship to the water's edge. Mortality of eggs was investigated further by the establishment of a hatchery which ensured that some clutches survived predation. Embryonic development within nests was monitored to assess normal levels of fertilisation and mortality during embryogenesis. The sex ratio of hatchlings was investigated and correlated with ambient sand temperatures. incident global radiation and sand colouration.