Cars, Planes & Trains - 86 free documentaries about ships & submarines.
Start with How Do Nuclear Submarines Make Oxygen?- Smarter Every Day 251 (30 min, Smarter Every Day), then Gigantic Overseas Autoliner (48 min, Free Documentary). All 86 documentaries here are free to watch from their makers' official uploads. To read deeper, the top-rated book on ships & submarines is Blind Man's Bluff by Sherry Sontag.