Oceans - 74 free documentaries about ships & the navy.
Start with Why This Zig-Zag Coast Guard Search Pattern is Actually Genius - Smarter Every Day 268 (27 min, Smarter Every Day), then How to Surface a Submarine in the Arctic Ocean - Smarter Every Day 260 (42 min, Smarter Every Day). All 74 documentaries here are free to watch from their makers' official uploads. To read deeper, the top-rated book on ships & the navy is Neptune's Inferno by James D. Hornfischer.