If you enter the "car drives through water" cheat, be sure that you have a "car hop" cheat
ready for some jumping, because when you are near a barrier that forbids you to cross the
water or drive straightly to it, just use the "car hop" cheat by pressing the left analog
stick firmly, that will make the 'car' not the bus or truck, the car should be like a
small 4 seated car, bigger that your character by 4 times no, trucks allowed!
so you're ready to cross the barrier JUMP and automatically your car floats by its wheels
then off you go!!!, 

PS: USE THIS OFTEN SO YOU WOULD ENJOY RIDING DOWN THE NEXT ISLAND 

THANKS GUYS -Jojo