We went to Altinkum last July. We went to the aquapark in Didim, not massive but plenty to keep the kids amused all day, not sure how much it cost but was very cheap. We were there in July and expected it to be really busy and having to que for the slides but this wasn't the case at all, only thing I didn't like was it is very very slippery around the pools and quite a few people had accidents.
There is a small fairground up towards the 3rd beach, we never went there we just passed it one day in the dolmus on way to the beach, maybe someone else can help you on this.
Hope this helps

Hi just got back from aqua park (about 1/4 mile from adaland). It is relatively new, we booked with first choice and with the world hotel/world club you get free access to the water park. i wouldnt say the water park is good, but i would say its brilliant for the kids and young at heart.
check out the aquafantasy website

Hi

Went to Altinkum last year and my partners and kids went to the one in Kusadasi (about an hour away) and they had a fantastic day and were told that one is much bigger than the one in Didim

As for a fair there is a small one just by 2nd beach which always looked busy from our apartment balcony and as long as you want basic rides and love the pussycat dolls and black eyed peas songs it will suit you

Hope this helps

Wendy