We took a rare tour of one of the US Navy's most dangerous warships - nicknamed the 'Sledgehammer of Freedom'

Daniel Brown/Business Insider

USS John Warner.

The USS John Warner, a Virginia-class attack submarine that was commissioned in 2015, is the US' third newest sub.

We got the chance to tour the Warner as it was docked at at Naval Station Norfolk.

Named after former US Senator John Warner - but nicknamed the "Sledgehammer of Freedom" by the crew - the Warner can perform a variety of missions for the US Navy, including surveillance, reconnaissance, search and rescue, as well as launch land attack missiles, torpedos, and mines.

The Warner, and submarines in general, are highly classified and rarely seen by the public.

But we got to take a tour of it - here's what we saw: