Bert and Ernie are enjoying a day at sea, when Ernie spots a character in the water, which Bert doesn't believe. Ernie dives under and meets Ethyl Mermaid, who plays tag with him. Meanwhile, a nasty rat parks his boat right next to Bert and begins tossing trash into the water. Ethyl agrees to meet Bert, but gets caught in some of the rat's garbage. Bert and the rat hear her air bubbles popping with yelling coming from them and offer to help. The rat attaches his anchor to the trash and pulls, setting her free. They then collect the trash from the ocean floor.