This is a Dora the Explorer Dive and Swim Mermaid from Mattel.  This doll is made to swim in your bathtub or pool.  All you have to do is wind her up (the arms are the winder), then straighten out her tail, and let her go.  When in the locked kneeling position, she measures approximately 10 inches tall.  When her tail is straight, she is approximately 14 inches long.  She has been tested, and she works fine.  According to a demonstration video found on Youtube, she tends to swim best when her hair is wet.  That said, she is in over all good condition with some wear from normal play.  See pictures for details.  No packaging, accessories, or anything else is included.