The Octonauts and the Hidden Lake

The Octonauts and the Hidden Lake is the 2th episode in the 4th series of Octonauts.

Plot synopsis
While the Octonauts are exploring Antarctica, It seems like no creatures are around, Until Shellington suddenly discovers a red lake hidden under the ice! Could there be undiscovered creatures living there?

Appearances

 * Only 4 octonauts
 * Microbes (Debut)