No, its four.
My four year old nephew is going with my nine and ten year old daughter and son. My kids have been twice before - and honestly I think are way too old for it now (my son last went at eight and was bored - he was also obviously the oldest kid on the pontoon), but are willing to go with their cousin. So I'm obviously comfortable (though if it were me, I'd give the eleven year old an option to bail on it).