[emptyspa_e]

Per Wikipedia, 68 active US subs. All are nuclear powered, 18 carry nuclear weapons.

[ethbro]

Wikipedia apparently has different numbers on different articles.

You're only going to be shadowing ballistic missile submarines with attack subs, which means (total nuclear boats) - (18 Ohio class).

Based on the individual class pages (LA, Seawolf, Virginia) there are 53 active SSNs.