In Khon Kaen City.
It’s a big city! There are a lot of restaurants, coffee shops, bars, spas, etc. We think you can take it from there.
The entry fee to the zoo include animal viewing and water park. You can find more detail about animals in the zoo here http://www.khonkaen.zoothailand.org/en/index.php.
Water Park is decent (photo by Big Nipat).
Near Si Chompu
Hiking and caving at Phu Pha Man National Park. We recommend Phaya Nakkarat cave. Hike 15 min up hill, then about 2 hours caving and take exit to Kred Kaew cave. High clearance vehicle, good lighting and private guide from National Park is necessary cause you will be hiking in a maze in pitch black.
Phaya Nakkarat hiking and caving