Entering the Vasa Museum for the first time is a jaw-dropping experience, as your eyes adjust to the gloom and you realise the monstrous size of the Vasa - the largest and best-preserved ship of its kind in the world. Built in the 1620s when Sweden was at war with Poland, the Vasa had two gun decks and 64 cannons, making it the mightiest ship in the fleet. Unfortunately, the gun decks and heavy cannon made the ship top-heavy. During a stability test, in which 30 men ran back and forth across the deck, she nearly toppled over. Still, the king needed his ship and the maiden voyage went ahead. But only a few minutes after the Vasa set sail from near present-day Slussen on 10 August 1628, she began to list to one side. The gun ports filled with water and the ship sank after a voyage of only 1,300m (1,400yds). Of the 150 people on board as many as 50 died - the number would have been much higher if the ship had reached Älvsnabben in the archipelago, where 300 soldiers were waiting to board, before it went down. The reason the Vasa was so well preserved at her recovery in 1961 - 95% of the ship is original - is because the Baltic Sea is insufficiently saline to contain the tiny shipworm, which destroys wood in saltier seas.
Head first for the theatre to watch a short film about the Vasa and her discovery by amateur naval historian Anders Franzén, who spent five years searching for her with a home-made sampler device. On your own or with a tour (there are several daily in English) you can walk around the exterior of the 69m-long (225ft) warship and view the upper deck and keel from six different levels. The ornate stern is covered with sculptures intended to express the glory of the Swedish king and frighten enemies. No one's allowed on board, but you can walk through a re-creation of one of the gun decks. Although the ship is obviously the main attraction, the museum has expanded over the years to include exhibits on 17th-century life and shipbuilding, and features numerous models and dioramas, as well as computers that enable you to design ships and test their seaworthiness. In a fascinating, eerie exhibit down by the keel, the skeletons of ten people who died aboard the Vasa are on display, as are reconstructed models of how they would have looked alive. The museum's restaurant has a dockside view of Skeppsholmen, and its gift shop is stocked with everything the Vasa enthusiast might need.