I remember this game having an option where you could print out a full-colour map of the Lego island. This printed over about 8 pages, and my dad was pretty mad when he found out how much ink I'd wasted on that thing.
But yeah, I played enough of Lego Island at a young age that the game is deeply imprinted on my brain. Looking back it's interesting how it presented itself as a sandbox but it did have a story mode of sorts, it was just hidden. If you delivered a pizza to the prison when playing as the pizza delivery boy then the prisoner would escape and you'd chase him down over a series of missions. The fact that he used a pizza to escape from prison still confuses and haunts me to this day.