It forms ferric oxide (rust).
How Does Iron React With Oxygen And Water?
Iron when immersed in water and exposed to air, will begin to corrode. They did an experiment once on tv where they immersed a car and it worked as a huge battery. That is because iron through processing is compressed, water and air causes it to release energy and will rust. That is just the metal breaking down
It will rust, i.e. Ferric and ferrous oxides will form