I've seen many documentaries on Titanic and they've all been really good, but Titanic: Secrets Revealed is definitely one of the best ones I've seen. It features interviews with Titanic survivors and tells us about the people and the captains, etc. on board. Historians and Authors talk here too and we see real footage of the Titanic and much more too. As well as recommending this, I also recommend the movie, Titanic. It's a brilliant movie.