Luke welcomes his friend Matt and his girlfriend Suzie that come from London and Matt's sister and Luke's former girlfriend Kate that comes from Sydney to sail with him and the sailor Warren in a sailboat. However, the vessel hits an underwater rock and capsizes with an opening on her bottom. Luke advises that they should swim in the north direction to reach the Turtle Island, in Queensland, Australia, while they have strength since there is a current moving the boat in the opposite direction of land but Warren prefers to stay on the hull waiting for help since there are sharks in the water. The quartet swims, but they are hunted by a great white shark.