ThunderCats (1985)

S1E21 Dr. Dometone

An elderly scientist reaches out to the Thundercats for assistance in rescuing the oceans of Third Earth. Years ago, a fissure formed at the ocean's floor, allowing water to seep into the planet's core. Dr. Dometone crafted a plug that successfully sealed this breach, preventing disaster. Now, a nefarious miner named Scrape aims to extract the plug and exploit the valuable rock beneath the ocean. The Thundercats team up with Dr. Dometone and his amphibious robot, Herkie, to thwart Scrape's plan and protect their world from utter ruin.