We went on a Sunday (in September) and experienced minimal queues. I thought going at a weekend would be a recipe for long queues but someone suggested that it is changeover day. That was great advice.
OK, we queued for 30 minutes for the rollercoaster but I myself liked the "hard" rides e.g. "Air Race" & "Top Swing" (thumbnail photos at http://park.aquashowparkhotel.com/?p=tema&pg=3&lang=pt & http://park.aquashowparkhotel.com/?p=tema&pg=15&lang=pt respectively) which were sited 50 feet from each other and which there was no queuing for. I literally got off one and walked straight onto the other, and shuttled between the two. I did that half a dozen times before starting to feel that I had overdone it - but came back later to do it again. Suffice it to say that my aerial views of the park were as much inverted as right way up!
They are both great rides. Top Swing gives you that great "butterflies-in-the-stomach-as-you-go-over-a-hump-back-bridge" feeling.
Get a locker key on entry from the shop (go through main entrance and then visit the shop in the building immediately to the left of the main entrance). It costs 3 Euros plus a returnable 7 Euro deposit. It's a fair walk back from the lockers if you don't and you want to get on the popular rides e.g. the rollercoaster asap.
For reasons unknown to me, there is a set of turnstiles in the middle of the park which you have to go through to access the other half of the park. I suppose it is a crowd safety measure (but there were no crowds when we visited). We went through here to get to our lockers and then climbed a small hill. At the top on the right there is a large water area for young children, approximately the area of 6 tennis courts and with water about 1 foot deep. There is a cafe and toilet block adjacent to it. OK, this is dull but important - a tiny tots toilet tip. We made the mistake of keeping of taking our daughter to the adult toilets here, completely unaware for most of the day that on the adjacent side of the same toilet block there are dedicated, superb, unisex kiddie toilets which you enter straight from the water. There are half a dozen tiny toilets down the left wall with pink partitions, and half a dozen tiny toilets down the right wall with blue partitions. On the wall facing you is a row of tiny washbasins, all under knee height. My daughter loved it. We thought it a great idea not least because it encourages kids to use the toilet instead of the, err, pool - as I said, you enter straight from the water area through a large open front (there is no door, just a large opening, but you can't see the toilets through the opening). I only discovered it late in the day and heard another parent saying she wished she had discovered it earlier.
We had no problem with the photos with animals. Staff tried to take a photo of us literally as we entered the park (the first I knew was when they were taking our bags off us without saying anything which I disliked) - I simply politely declined and we were never bothered again, anywhere in the park. Those who pay for photos are subsidising your visit... Having said that, I saw plenty of people having their photos taken and some looked good.
Where to dump your towels? We took lockers in the children's area (there are three locker blocks at various locations). To the left of those lockers is a wall. The shade there increased during the day and was a good spot. Another good area (but far less central) was in the shade of the "White Fall" (see photos at http://park.aquashowparkhotel.com/?p=aqua&pg=6&lang=pt). The latter got more popular as the day progressed.
Buy your tickets in advance - many ordinary shops sell them with a 15% discount. Under 5s are free.
This isn't a world leader in water parks (hence my star rating) and we went with that in mind. I like "tough" rides but even I had a great time, as did my wife and daughter.
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