The H.L. Hunley was like a really big metal fish that could go underwater. It was made during the Civil War and was used by the Confederate army to attack Union ships.
The people who made the H.L. Hunley wanted to make it extra special, so instead of being on top of the water like most boats, it could go underwater. They had to turn a big hand crank to make it move - kind of like riding a bike, but with your hands instead of your feet.
Sometimes when the H.L. Hunley went underwater, it would tip over and the people inside would have to use a special tool to right it, like when you fall off your bike and have to get back up again.
One time, the H.L. Hunley attacked a Union ship and sunk it. But then something went wrong and the H.L. Hunley also sunk. It took a really long time for people to find it, but when they finally did they found out that everyone inside had died.
Today, the H.L. Hunley is in a museum where people can go see it and learn about its history.