I want to go to my friends party but my panrent wont let me...?

ok, my friend is having a birthday party and its about 5 hours long. Its at a big amusement park and theres 3 of us going; me (12) , her (12) and another friend (14) . but they think im going to get abducted or something, but im responsible and careful. so how to i persuade them into letting me go, and make them realise that even tho theres no parent there im not going to get taken away, because im in a group?