Their mouths curve naturally in a smile shape.

They are beautiful! :)

They are! Did 123rf say where the picture was taken?

I've been wondering where this is.

It doesn't say. I just did a reverse image search and I'm finding it on various stock photography sites.

http://www.fotosearch.com/CSP859/k8592821/

http://www.123rf.com/photo_12269985_the-bottle-nosed-dolphins-in-sunset-light.html

Thanks -- reverse image search could not find it for me, either. :(

I love the image nonetheless. I'm always looking for more!