Furthest ball I have ever seen hit in person one hopped a 300 ft fence, so it landed @ 290. Awesome player who is going to Florida next year.
My DD practices on a field with a fence that's 270 feet. If the grass is cut just right and the wind and sun are aligned, she can hit balls that roll to the fence. The fact that there are high school players who can hit balls over that fence, even if few and far between, is pretty humbling.