I used to get that hydro jet thing, and fly through the water, with the huge wake flying behind me.
I did too, i tried to catch up with the boats that go around the islands.
That one thing that was always too hard for me to do:
Get yoshi on the boat, float over to the metal bar sticking out of the water, and jump onto the island with the coconut palm tree, and destroy the yellow goop to get into the warp pipe.
He always died before i made it D: