Try using the U button, to Use the raft. Speaking of the U (use), E (examine), and P (pick-up) buttons, I sure hope you ppl have been trying all of 'em on every object you can find. I rather enjoyed the 'Pick up the Moon' comment myself, but then I was always a big fan of nostalgia.
You: What is the Secret of Monkey Island?
Me: The secret is, is that there is no secret.
You: Huh? But what about Big Whoop, the Three-Headed Monkey, and/or The Big Honking Monkey Robot?
Me: Oh *THOSE*. Well you really can't call them secrets now, can you?
Me: Well everyone knows about them now, don't they?
You: Well I guess...
Me: See, there you go. Since they're not secrets anymore, there is *NO* Secret of Monkey Island. So what has this taught you?
You: Never to spend, $39.99 on a computer game.
Me: Tsk, Tsk, BAD MONKEY!!! *Whack!* Besides, that was more or less a direct steal from an answer to the first Monkey Island game!