This was taken at Papailoa Beach on the North Shore. It was one of the main filming locations of the TV series "LOST". In the summer the sand is wide, the water is calm, and you can almost always find green sea turtles eating and basking in the sun. In the winter though, tons of sand along North Shore beaches are removed by high surf and many rocks are exposed. Papailoa becomes turbulent, even dangerous. Waves smash into the exposed rocks and green algae, creating little waterfalls and tidepools everywhere. In the summer, the sand will be re-deposited, creating a nice wide sandy beach again.
