Also known simply as The Vasa Museum Stockholm
A few ships were created to help defeat Poland for King Gustavus Adolphus in the 17th century. One of them the VASA sank on its maiden voyage in the Harbour of Stockholm. It was recovered and restored and the museum is essentially about that. It has the actual ship forming the main article of interest but there are other things too such as the reconstruction of skeletons found on-board and information about what it would have been like on the ship.
The museum is one of the main attrcations in Stockholm and crowds are controlled so expect some queing. This does mean that its a great experience once inside and so with some planning it is a really good thing to do. Won't say must do as some people may not be so interested in the subject though everyone will appreciate the recreation of the VASA inside.