Hi Cath, the waterpark is around 30 - 45 mins from Lara beach. You could get a dolmus from outside hotel, but you would probably have to change to another dolmus in Antalya city. You could also get taxi, not sure how much that would cost, but agree a price first. There may also be a trip there from the rep in hotel or from a kiosk outside the hotel.
There is also a great waterpark called Troy in Belek (doesn't have large,high, slides though - if that is what you are looking for), there is also a dolphinarium there, but it is quite expensive though.!
I have always found 'guest relations' at these Lara hotels to be excellent, and they would have all the details and be able to help you.
Denny

Hi Denny thanks for your help.
cath

That's go to hear, as i'm going to Lara Beach in september with my 7 year old and he would love to go to a water park.

Thanks Kirstin