Wadi Adventure is not really a theme park, think more of an activity park including surfing, kayaking, white water rafting located in a desert mountain environment and yes, everything is man made.
It actually looks very nice, but not very nicely organised. You need to pre-book all your activities, otherwise you can just use the pool, it’s slightly chaotic and the staff doesn’t know how to deal with unexpected situations, like injuries.
Trust me, it is very easy to get injured in this place.
On the other hand, it is clean, well maintained and decent food selection is offered.
If you up to something little bit different, or feeling adventurous, this could be a fun day and town of Al-Ain is nice to visit too.
But do some research before you go.