Clark Roberts 
Fourth of July on Monster Mountain [EPUB ebook] 

The quarter of cousins are back, and this time they’re celebrating our nation’s birthday at the wacky uncle’s dinosaur-themed water park.
It’s the grand opening of Uncle Victor’s Dinosaur Adventures Water Park, and Uncle Victor has a top secret water slide only open to the family. Even better, the The Time Machine water slide is built inside of Monster Mountain and is complete with waterfalls!
Nothing is ever as it seems with Uncle Victor and the top secret Time Machine might be more than the kids bargained for, as they’re thrown into a world teeming with dinosaurs and one very odd werewolf.
Join the whole crew, including Miss Penny and Mr. Fright, on their next wild and soaking wet adventure!