All of the expedition footage was shot at sea on a US government research vessel above the wreck in May/June 2004 as part of a National Geographic expedition.
The primary character is scientist Dr. Robert Ballard who is the co-discoverer of the wreck of the Titanic.
The women you see ascending the full-scale recreation of the First Class stairs are an avid mother-daughter collector team - everything they are wearing in this scene is period and accurate to the era.