Your Stage : Northwood - Submarine Short by John Fraser

Th military has a process for requesting use of their equipment. That's about all I know except they look carefully at the script to ascertain whether the story makes the military look good.

What era? There may be WWII sub memorials. Those are probably under Department of the Interior. Hollywood mock ups and sets.

That depends on if you need an actual submarine, or a submarine set. One is certainly easier to obtain than the other. As both a Navy veteran and a filmmaker, I'd say it's impossible to get on a current nuclear-type class sub, mostly due to security clearances that you, as a civilian, simply cannot obtain. I assume at least the US Military? Regardless, I highly recommend using real military crew and talent for your project, and can recommend some great resources, as well as offer my opinion on which resources to avoid.

In the US, you’d want to hit up the museums in New Orleans to see about use of exhibits or reproductions. They can help you find a set. In the Uk, same story in Gosport.

Recently went down the road of seeking US military approval for use of locations, This was with the Air Force. While a short film, they insisted upon distribution prior to approval. We secured a distribution deal, the AF said the distribution was not significant enough. They passed.

Maybe you can find a museum that has some scrap aircraft hulls. While not the same, the shape is right to fabricate a set.

Unlikely you'll get access to or even onboard a nuclear sub in today's fleet.

John-for what it's worth, San Diego has a maritime museum downtown which does include a submarine that they allow people to walk through. If you need a set, I would think that finding something like that nearby would be a hell of a lot easier than an actual, working sub for all the reasons others have expressed.