Excellent info on Titanic
In this book, Dr. Robert Ballard explains how he located the Titanic's shipwreck 73 years after it sank. The story of the Titanic is told: main facts about the ship, the voyage, the sinking, etc. Ballard then goes on to tell about his expeditions, and the condition of the ship and debris as it was found. The underwater photos that Ballard obtained are equally informative.
"Exploring the Titanic" is actually just a reduced version of Ballard's bestseller, "The Discovery of the Titanic". I would recommend "Exploring the Titanic" if you just want to learn basic facts, or for young readers. On the other hand, "The Discovery of the Titanic" contains all the same information and much, much more (especially for advanced Titanic enthusiasts).