During a game of tag between SpongeBob and Patrick, they accidentally go off a cliff into an underground cavern with a shipwreck called the "Mauna Loa." They then spend the day playing and exploring the ship, soon discovering a gigantic hoard of gold coins. The next day, despite SpongeBob and Patrick wanting to keep their "hideout" a secret, Patrick repeatedly and loudly talks about the Mauna Loa in the Krusty Krab and even wears a shirt that says "Follow Me to the Mauna Loa". Mr. Krabs then finds out about the hideout after Patrick pays for a Krabby Patty with one of the gold coins. He claims that the Mauna Loa houses the world's largest hoard of treasure and that he has been searching for it his entire life. Therefore, he follows them down to the ship, where SpongeBob and Patrick discover him and they show him where the hoard is. However, as Mr. Krabs celebrates his lifelong goal being achieved, SpongeBob notices that the gold coins are actually tokens and have no monetary value. Mr. Krabs thinks that the hoard is a decoy and thinks the real treasure is hidden somewhere else on the ship, but upon further exploration, the trio finds a ticket booth, a height restriction chart, and a plastic skeleton wearing a captain's uniform. From this, Mr. Krabs deduces that there is no treasure and that the ship is simply an abandoned amusement park ride.
Mr. Krabs angrily decides to leave, but then realizes he could make lots of money by opening the hideout to the public as an attraction, although he refuses to pay to have the ship properly repaired (being the cheapskate that he is). The ride proves to be quite popular despite the obvious dangers (it swings back and forth like a pendulum, yet there are no safety harnesses installed, which causes the riders to be tossed around), and many citizens ignore the required safety height so they can ride it. SpongeBob and Patrick are at first dismayed that their secret hideout is no longer a secret, but eagerly join in anyway.
As expected, the old ship starts to lose bits of wood during a cycle, and one of the pieces hits the speed control, turning it from "slow" to "beyond comprehension". The ride picks up speed and starts spinning around the swing, ejecting many riders and terrifying everybody except SpongeBob and Patrick, who are having the time of their lives.
Soon enough, the high speed causes the swing to collapse and the ship shoots up into the air, before plummeting to the ground and exploding into a pile of smithereens on impact. SpongeBob and Patrick emerge from the rubble unhurt and compliment how awesome they thought the ride was, oblivious to the carnage that surrounds them. The other riders and bystanders also begin to emerge from the rubble covered in various injuries and angrily blame Mr. Krabs for putting their lives in danger.
An officer shows up and arrests Mr. Krabs for operating a danger to public safety, and the hideout is condemned and boarded up, much to the sadness of SpongeBob and Patrick. They then leave to find another hideout and accidentally fall into another pit into yet another underground cavern containing the real Mauna Loa shipwreck. The episode ends with SpongeBob asking Patrick if he can keep a secret, and Patrick replying "Nope".
In real life, Mauna Loa is actually the largest volcano in the world (in terms of volume). There was also an actual ship called the S.S. Mauna Loa, which sunk.
There are 50 anchors in the title card.
This is the second time a cavern appears. The first was in "Chum Caverns."
This is the fifty-eighth episode with the title's name being a part of the story.
After the ship crashes, SpongeBob, and Patrick hug, when Patrick is talking, you can see all his teeth in his mouth for about a fraction of a second. However, in other episodes, Patrick appears to have only one tooth.
This is the first time Mr. Krabs calls something a "hunk of junk," making "The Masterpiece" the second time.
Mr. Krabs only pronounces Mauna Loa two times correctly, when he discovers the token and when he goes into the Captain's Quarters.
In previous episodes, like "Shell Shocked," Mr. Krabs was in the dumpster, and when Mr. Krabs found out that SpongeBob and Patrick knew about the Mauna Loa, he said that he was looking for the wreck in dumpsters, which means Mr. Krabs could have been looking for the Mauna Loa that time.
The beginning of the episode is similar to the beginning of "Patrick SmartPants" except SpongeBob fell off a cliff but did not break his head and turn smart.
The word "Mauna" is in Filipino language, it means to "anticipate."
In this episode, Patrick does not understand (or care) about keeping secrets. However, in "The Secret Box," he not only understood keeping secrets, he was adamant about keeping the contents of his box a secret. He even admonished SpongeBob, telling him that if he showed him what was inside, and then it would not be a secret anymore.
When Patrick flings the token at SpongeBob, if one were to pause the screen image, the token clearly reads "No Monetary Value."