Him: “You gonna go see the boat museum?”
Me: “The what?”
Him: “The boat museum. It’s a museum with a boat in it.”
Me: “…just one boat?”
Him: “Trust me. Go see the boat.”
He was right. One of the coolest museums I’ve ever visited in my life.
The Royal Amory (https://livrustkammaren.se/en/home/)
A lot of old items from royalty and nobility. If you ever wanted to see how armor was deemed bullet-proof they have some dented chestplates that shows it off.
Swedish Army Museum (https://armemuseum.se/en/start/)
Army history from the 1500s and through the Cold War. Old collections of weapons, explanations of how huge armies were maintaned and fed and iirc they also have a huge old soviet missile.
My wife and I visited it once when we spent a weekend trip sightseeing in Stockholm. It was one of the best museums I've been to.