|Original broadcast||April 17, 2009|
|Series||The Secret Saturdays|
|Episode number||11 (formerly 12)|
|Overall episode number||11 (formerly 12)|
|Written by||Todd Garfield|
|Directed by||Scott Jeralds|
|Previous episode||The Swarm At The Edge Of Space|
|Next episode||Black Monday|
Eterno was the eleventh episode of Season 1 of The Secret Saturdays. It is the eleventh (formerly the twelfth episode by Cartoon Network because Black Monday was thought to be a better way to start the season) episode overall. It premiered on April 17, 2009.
The water in the Middle East is being crystallized into salt. The top scientists of the Earth, including the Saturdays, are sent to investigate ways the water can be restored. What they encounter is a salt beast known as Eterno, who seeks the Methuselah Tree to end his misery of unquenchable thirst, a tree that makes all the water on earth. When Drew and some local villagers refuse to lead him to the hidden location of the tree, Eterno turns them all into salt statues. Now Zak must ignore his new position as a person regulated to the sideline. Wadi leads Zak to the tree, but steals one of its flowers, sending Eterno and a group of local cryptids (the Centiscarabs) after her. Eterno takes the flower from Zak and drinks all its sap, which turns him dust. Doc is able to use the root of the plant to synthesize additional liquid and turn the water, his wife, and the villagers back to normal. And at the end Zak receives thanks for helping them save the village, and his mother. Seeing of how Zak is a big help to everything, his parents decide to let Zak participate again in missions, despite the risks.
- Despite having to sit this one out by his parents, Zak, like on all occasions, takes matters into his own hands.
- Wadi and her father make their first appearance in this episode.
- Zak was told to sit this one out, but in the end, he gets promoted back to being an ally, for saving the village people, most importantly, for saving his mother and Komodo.
- Zak ends up being promoted as an ally for rescuing the village and his mother.
- Wadi pantses Zak twice in this episode, probably because she likes him a lot.
- Zak wears heart-shaped boxers.
- Sometimes Zak's taller than Wadi, sometimes Wadi's taller, and sometimes they have the same height.
- After Eterno touches Doc he can't move his leg, but when Zak appears with Wadi and Fisk, he can.
- When Wadi begins to read Eterno's story, they are in the cave where they found the scroll, but when she is finished, they are standing outside near the water turned to salt. However, it may have simply been they moved outside during the story.
- Doc says, "What was I thinking? Sending three children alone?" He didn't send Wadi, and Fisk is a cryptid, not a child. However, since Fisk was adopted as the Saturdays' son, it's likely he would consider Fiskerton as a child.
- Ben 10: Zak going against his parents wishes, and solving the problem himself, is similar to what Ben Tennyson's future son Kenny does, after his father told him to sit out his fight against Kevin, and for not letting him help a lot on missions.