Save the Mermaid Kingdom

 is the fifteenth episode of "Backyardigans x Frontyardigans" written by Hornean.

Captain Andrew and his crew journey in the undersea vehicle to study the underwater activities. But soon they heard a call for help from four mermaid sisters (Uniqua, Ramona, Tina, and Penny). They took them to the Mermaid Kingdom where King Austin tells them that a series of quakes is threatening the kingdom. Can Andrew and his crew find out what's causing the shaking?


 * Andrew (Captain Andrew)
 * Thomas (Lieutenant Thomas)
 * Martin (Medic Martin)
 * Jason (Ensign Jason)
 * Pablo (Scientist Pablo)
 * Tasha (Photographer Tasha)
 * Henwen (Engineer Henwen)
 * Sophie (Gardener Sophie)
 * Victor (Chef Victor)
 * Kathy (Chef Kathy)
 * Moe (Professor Moe)
 * Austin (King Austin)
 * Uniqua (Mermaid Uniqua)
 * Ramona (Mermaid Ramona)
 * Tina (Mermaid Tina)
 * Penny (Mermaid Penny)
 * Tyrone (Vizier Tyrone)


 * "Swimming, Swimming"