What Causes the ‘Rust’ on Ancient Ships?

The rust on ancient ships is caused by something that happens when water and metal hang out together for a long time.

Imagine your toy car gets wet from the rain, and then you leave it in the sun. After a while, you might notice some parts of the car looking like they're getting tired, maybe they turn a reddish color or feel rougher. That’s kind of what happens to ships made of iron or steel when they sail across the sea for many years.

When water (especially salty seawater) touches metal, it starts a little reaction, like when you mix baking soda and vinegar. This reaction makes the metal lose its shiny look and turn into something called iron oxide, which is what we call rust. The salt in the sea helps this reaction happen faster.

Ancient ships, especially ones that sailed far and wide, would sit in water for a long time. Over years, sometimes centuries, the water would slowly eat away at the metal parts of the ship, turning them into rust. That’s why we see so much red stuff on old shipwrecks when archaeologists dig them up.