Thank you, Simone. #91 is VERY hard to see. The treasure chest is hiding on a small lower level, where you really don't want to be otherwise.

How do you unlock the *777 ball (2nd from left on the bottom row of balls)? I had gotten it once before but, after having to reinstall the game on a new phone, don't remember how!

FYI - To the left of the volleyball will be a tennis ball. Like you say, "you can't go back" but I'm certain it's within the first 200 holes. (I had to reinstall and restart on a new phone, so I'm feeling sure about that.) Spend some quality time cruising through the first 200 holes with binoculars.