Rafts have played an important roles in many key events in Lost. Two rafts were built by a team of survivors led by Michael, in hopes of finding a shipping lane and securing rescue for the castaways. They were built in a catamaran style, the style which were used by Polynesian Islanders to travel the Pacific Ocean. An inflatable raft was provided by Desmond's sailboat, Elizabeth. A raft was used by the Oceanic Six, Frank, and Desmond until they were rescued by Penny. The Oceanic Six then used it as they were dropped about 8 hours away from the Island of Sumba as part of their cover story.
Michael first suggested the raft while Sayid, Jack, and Shannon were looking at Danielle Rousseau's map of the Island. ("Special") The first raft was built by Michael in an attempt to get his son Walt off the Island. Sawyer "bought a ticket" on the raft by giving necessary parts to Michael.
Before it could be launched, the raft was set on fire and destroyed. Jin was suspected of starting the fire since he had a grudge with Michael, but Sun proved his innocence. That night, Walt admitted privately to Locke that he had burned the raft because he did not want to leave the Island. ("...In Translation") Walt later voluntarily confessed it to Michael. ("Born to Run")
The second raft was also built by Michael, but this time Walt assisted his father in the construction. After having relationship issues with Sun, Jin wanted to leave the Island, so he too helped Michael with construction. Sawyer kept his "ticket" on the raft by "keeping guard", a job which he performed half-heartedly.
Before they could launch the raft, Sun attempted to poison Jin in order to keep him on the Island; however, Michael accidentally drank the poisoned water. The plan was originally thought up by Kate, who also wanted to be on the raft, in order to avoid media scrutiny if-and-when they were rescued.
Sawyer was invited back onto the raft after he revealed Kate's secret status as a fugitive, which lead to her being the prime suspect of the poisoning. Jack decided to keep Sun's secret. ("Born to Run")
The second raft was launched by the entire Survivor community minus those on the trek to the Black Rock with Walt, Sawyer, Michael, and Jin aboard. At sea, they encountered the Others, led by Tom Friendly, who destroyed the raft after they kidnapped Walt. ("Exodus, Part 1") ("Exodus, Part 2")
Inflatable raft from the Elizabeth
An inflatable raft was aboard Desmond's sailboat, Elizabeth. It did not have an engine, and was operated by oars.
A life raft was taken from the freighter Kahana and placed aboard Frank Lapidus's helicopter shortly before it took off from the freighter for the last time. After the helicopter crashed, Jack, Kate, Sun, Hurley, Sayid, Desmond, Frank, and Aaron floated aboard the raft as they recovered from crash of the helicopter. The Oceanic Six, along with Desmond and Frank, were aboard the life raft as they were discovered by Penny on her vessel the Searcher. A week later, the Oceanic Six paddled the life raft to the Island of Sumba as part of their cover story. ("There's No Place Like Home, Part 2")
Raft (Bésixdouze expedition)