These water parks are dangerous. Children and adults die each year in these places. They do not have enough life guards on duty (some places have none even though they're supposed to have them) and they tend to be overcrowded. You do need to be a skilled swimmer if you want to be assured some amount of safety. There are thousands of pending lawsuits against various water parks nationwide. The number one cause of death is lack of adequate supervision on the part of the park staff and child chaperone/parents, and a major contributing factor is no swimming skills.
See:
http://www.rideaccidents.com/water.html
http://www.ehow.com/info_###-###-####_dangers-waterparks....
It is impractical to believe someone could save her if she were to get into trouble. Children drown mostly because they are so crowded and chaotic, no one notices they are missing or in distress until it is too late. In the past, children have been accidentially crushed or hurt in the tubes, others drown in the wave pools. You have no control over the other swimmers and teens tend to be very obnoxious and uncaring of younger children.
Whether my kids could swim or not, I would avoid those water parks. I think they're so dangerous and not worth the trouble. Pools are bad enough, but it is much easier to see what your child is doing in that situation versus the very unpredictable water parks. So IMO nix the invite. I wouldn't put my precious cargo in harms way for a silly outing. This has nothing to do with holding her back from having fun, it has to do with common sense safety. Remember, no matter how good of a friend you may have, if nuck comes to tuck and something goes wrong, it's her own child she's going to be looking out for, not yours. It's human nature. I think your friend is wack wanting to take on a responsibility like that. If anything should happen to your daughter, she's going to have to live with that for the rest of her life. I say if you want your child to do stuff like that, it should be on your watch. She can't fend for herself. She can't swim. She's too young. She's not that woman's own child. She'll be in a strange environment. She'll be in a huge chaotic water park with strangers and no skills, no no-how, no one to watch out for her safety. I think that's nuts...and wouldn't even give it a second thought.
If you need convincing about the dangers of pools and water park dangers, here in my neck of the woods a local family is still reeling from the near death of their 6-year-old child after her intestines were sucked out of her body after she got sucked under water into a country club's faulty filtering system. They won a million dollar settlement, but the girl has to live in a facility with a colostomy bag for the rest of her life.
This weekend, at a different local country club, a 6-year-old boy who couldn't swim, died at his friend's birthday pool party. He drowned because no one noticed him in trouble. There was no guard on duty and it was up to mom (host) of the party to keep an eye on all of the kids. Her heart was probably in the right place, but she clearly took on too much and the boy's parents trusted that mom too much, and now they are all going to have to live with that for the rest of their lives.
Last but not least, no insult intended, but I have to say if you admit your failing about teaching her to swim, why on earth are you letting her get into a pool...and unattended?
Statistically, you are upping your chances for a tragic water accident. Yes, experienced swimmers drown, but it's a guarantee if you don't know how to swim.
Please, for the sake of your daughter, save the money you'd spend on this nonsensical trip and spend it on getting her some swimming lessons so she CAN be safe.
My family has had two swimming tragedies. One ended happily as the child was revived and is okay. The other ended in a death. This is not something to take lightly. Hurt feelings do not compare to the pain and horror of losing someone in a drowning accident.