I constantly get people coming to this site by searching for "scary optical illusion", I've seen many optical illusions but I wouldn't call any of them scary. Unless of course you are 4 years old. I mean if you were very young then this illusion might be scary.
Personally I love this illusion it is a special summertime illusion that the whole family can enjoy.
For those of you that get to the beach this year try your own illusion and send the picture in to this site. I might create a special section for do it yourself illusions. This won't be limited to beach illusions, any image that tricks our perception is welcome.