"Gorillas on the Mast" is the fifth episode of Season 31.
Synopsis
After a trip to Aquatraz Water Park, Lisa becomes determined to set free Springfield's most vicious animals in captivity. Meanwhile, Homer fulfills a lifelong dream of buying a boat, and quickly realizes boat ownership sucks.
Plot
The Simpson family visits the Aquatraz Water Park, where Lisa notices how unhappy the animals are behind glasses, including a penguin funeral, while Homer notices how much fun boat owners have, remembering how much he wanted it as a kid while fishing with his father.
A boat salesman notices Homer watching the boats and convinces him to buy one. Bart, Lisa and Willie go back to the water park to free the whale trapped in it, with Bart finally understanding altruism and liking it. Homer takes the family on a ride on his boat, the Something's Fishy, and even Marge agreed it was a good idea to buy it.
The next rider on the boat is Grampa but when they return to the pier, the boat starts sinking, and Raphael offers his help as a mechanic, while Bart is sharing a plan with Milhouse to free other animals on his newfound spirit of altruism.
Homer offers Lenny and Carl to share the boat, and the expenses to fix it. Bart and Milhouse go to the Springfield Zoo and free a gorilla, Lolo, but it goes on a rampage, while Milhouse gets caught by two tigers.
Bart calls Lisa for help since the police are useless on capturing it. Homer starts co-owning the boat with even more people and the boat sinks due to the weight. The gorilla rampages at the Springfield Elementary School and Lisa stops him using Seinfeld to calm it.
Lisa brings Lolo home to help it go back to a life of freedom, then brings it to Dr. Goodall at the Pennsylvania Ape Reserve where he'll be loved. At Moe's Tavern it somehow ends well when Homer convinces the co-owners of being as good as someone who owns a boat because they owned one for 5 minutes.
