Captain Planet and the Planeteers - Season 1 Episode 12

Gi and Ma-Ti investigate polluted areas of water, suspecting Sly Sludge is pouring garbage and sewage there, and Ma-Ti is pained from hearing many cries for help underwater. Gi goes down to examine pollution levels, and is attacked by Sludge's robotic octopus, losing her oxygen-tank and consciousness. She's rescued by Pontus, a resident of the secret underwater city Oceanus, and discovers that the protective dome around it is leaking from the contaminants. The civilization's Council forbids her leaving to bring the other Planeteers back to help, and the others, captured by Sludge, don't know where or if they'll find her. But with the pollution threatening animal and human life, they will need to unite to summon Captain Planet soon…