Secret Land The (1948)
This film is a documentary about Admiral Byrd’s military exploration of the Antarctic which won the Academy Award for that category. It is narrated by actors (and former military officers) Van Heflin Robert Montgomery and Robert Taylor.
It’s a very interesting film which portrays all aspects of the mission: from the preparation and planning of the expedition to the difficult time the Navy had getting there in the first place some interesting aspects of life as a member of the crew (e.g. at Christmastime) the winter wonderland that is Antarctica including its wildlife the finding of the original settlement and the construction of the new base the scientific and data gathering aspects of the mission and the overall exploration by air land and sea of the continent.
There doesn’t appear to have been any real reason for using the voice talents of three well-known actors of the time though there is a little drama when one of the reconnaissance planes goes down and its crew has to be rescued.