One of the main reasons the Vasa is so well preserved is that the Baltic isn't saltwater - it's just slightly brackish. In saltwater, shipworms will eventually

One of the main reasons the Vasa is so well preserved is that the Baltic isn't saltwater - it's just slightly brackish. In saltwater, shipworms will eventually eat away any exposed wood, but they don't live in brackish or fresh water. http://en.wikipedia.org/wiki/Shipworms http://en.wikipedia.org/wiki/Shipworms