The Secret Land (documentary)

(1948)
From Wikipedia - "The Secret Land is a feature-length 1948 documentary film about the United States Navy expedition code-named "Operation Highjump" to Antarctica in 1946. The film, which was shot entirely by USN and US Army military photographers, focuses on the mission to explore the polar region and evaluate its potential for military operations.
The Secret Land was narrated by actors Robert Taylor, Robert Montgomery, and Van Heflin, and produced by Orville O. Dull. It won the 1948 Oscar for Best Documentary Feature."