Challenge of the SuperFriends S01E06 - Battle at the Earth's Core

While sailing with Captain Pierre Marcel, the Wonder Twins and Gleek get sucked into a whirlpool. After receiving a distress call from the Wonder Twins, the rest of the Super Friends search for the twins, only to get pulled into the whirlpool themselves. They emerge in a Wonder Land that is below the Earth's crust. The Super Friends must now search for the Wonder Twins and rescue them.