well, when you get to the man "old explorer" i think. well the guy to get into mz, once he's in your screen. jump as far right as you can
woa! theres a river there
shift your screen to the right, and ban, you can hope over.
keep jumping right till you et the the portal in the top right section of the screen.
keep jumping in the top layer of the grass sections and the middle/right area has the huge snakes.
enjoy!