Description:  "The Underseas Explorers" is a 1961 animated educational cartoon about a team on an atomic submarine, the "Hydronaut," who travel the globe exploring the ocean's mysteries and encountering sea creatures, a topic sometimes confused with "The Deep" or "The Octonauts". It is often mistakenly called "The Undersea Explorers" or "Journey to the Bottom of the Sea". The series was recently rediscovered and is considered a classic for its ahead-of-its-time educational content and adventure storylines, such as the group's search for pirate landings and their encounters with giant octopuses.

Plot: A small team aboard the "Hydronaut" submarine travels the world's oceans, circumnavigating the globe and even passing under the Arctic ice cap.

Adventures: During their journey, they discover the original site of pirate landings and have encounters with various marine life, including a duel with an octopus.

Characters: The team is led by Professor Scott and includes other underwater adventurers.

Themes: The show was educational, designed to teach viewers about oceanography and marine biology in an engaging way.

Legacy: It has been rediscovered by animation enthusiasts and is sometimes compared to the "Johnny Quest" series for its adventurous and educational tone, though it's set underwater.