Codebreakers
S21E1
–
NOVA travels to Lake Baikal, the world's oldest and deepest lake, containing one-fifth of all the fresh water on Earth. Investigating Baikal from above, below and all around, NOVA charts its dramatically changing environment over the course of four seasons.
Episode
S21E19 · Season 21 · 19 of 20
Aired
20th December 1994
Network
PBS