The Slipslide Water Park is a water park Greg and Rodrick went to when they were little kids. They both have bad memories from it. Greg dislikes it because he didn't go on any rides with Grandpa because of a sign that said 'Under 48", must be accompanied by an adult'. Greg thought that meant you had to be 48 years old to ride alone, but it actually meant 48 inches. And Rodrick dislikes it because when his band, Löded Diper, was playing there, they had to use a bubble machine instead of a smoke machine because someone had switched the machines. The park appears in Diary of a Wimpy Kid: Dog Days. One day in Greg's summer vacation, Susan takes the whole family there for a family outing, but when they got there, they had to leave early as lightning struck and there was a traffic jam at the car park. After leaving, they had to stop for gas and suffer through Manny's made up jokes which didn't make sense after awhile. However, the Heffleys wasted another 2 hours because when they got home, Susan wasn't there, so they had to go back to the rest stop since she went to the bathroom without anyone noticing. In The Long Haul they made a reference to it.
"We went to a water park LAST summer but we got rained out"
- Diary of a Wimpy Kid Online (First appearance)
- Diary of a Wimpy Kid: Dog Days (First book appearance)
- Diary of a Wimpy Kid: The Long Haul (Mentioned)