For a time following their rescue, the members of the Oceanic Six kept the actual story of what happened following the crash a secret. In public, they adhered to a fabricated story about their time on the Island, using the excuse of being in "shock" as a safety for misquotes.
According to this story, Oceanic Flight 815 crashed into the Pacific Ocean, and only eight people survived the impact. Among those specifically said to have died in the crash are Ana Lucia,(4x01) Marshall Edward Mars,(4x04) Claire,(4x12) and Jin.(4x12) The survivors were in the water for over a day, afloat on cushions and debris, before washing up on the uninhabited island Membata. Jack was injured, and Kate dragged the survivors out of the water and onto a nearby deserted island. Kate administered first aid to some of the survivors and found food for them. Kate was said to be several months pregnant with Aaron at this time, which drew suspicion from one reporter.(4x12) At some point two of the original eight survivors died. After 103 days on Membata, a tropical storm washed up a raft with supplies and equipment necessary for their return to civilization. The group finally reach an inhabited island on day 108; photos of the six coming ashore were shown to the press to validate this rescue story.
Jack maintained this story under oath at Kate's trial,(4x04) and Hurley maintained it while under police questioning.(4x01) telling officer Mike Walton that he never met Ana Lucia. A grave marker for Jin in South Korea lists the date of the crash as his date of death. After Hurley was re-admitted to Santa Rosa Mental Health Institute, Jack visited him and questioned him to make sure his apparently deteriorated mental health status wouldn't diminish his adherence to the story. (4x01) Matthew Abaddon suspected the story to be false, and questioned Hurley about it. (4x01) After several years of maintaining the story, however, Jack told Kate that he was "sick of lying". (3x23)