My niece happened upon a map that had all 4 of the 5 bosses (and a trader) on the starter island, it took 3 full days of playing (not game days real days) to explore the coast of the entire starting island. I've since passed 800 game days and still haven't explored all of it (although to be fair I've explored other continents now).

I would feel much less enthusiastic about this game if its map were the same each time.