Get on your skateboard. Hold [Left Alt] to jump while you are riding towards the water. The grassy area near the Res-Q HQ would be a good place to try this trick. Just before you fall in, release [Left Alt]. If done correctly, you will see Pepper put away his skateboard just as if he were on land. Press the cursor keys to walk on water. : When you are ready to return to land, you will see Pepper fall into the water and get back out.