Ep 6. Reef Grief

Eliza and Debbie are experiencing some problems with their hasty father Nigel since they reached the sea which leaves both of them very surprised. Thinking they ought to leave him alone, they put on the snorkeling gear and go for a leisurely exploration. However, when they reach the coral reef, they find that the fish there are lying on their sides, no longer swimming. A closer inspection reveals that the coral is dead.

The two girls dive toward the shore, where their mother Marianne is helping to research the reef. Marianne tells them that the reef is dying from pollution, and the girls soon find the source of the problem: a fishing trawler that is illegally trawling on the reef. They try and keep up with the trawler, but it slips away.

Back on the research ship, Debbie talks to Sloan Blackburn, a girl who is roughly her age and whose father goes back decades with the Thornberrys. After the girls meet, Sloan finds out about the fishing trawler and the situation with the reef. She decides to join the Thornberrys in an attempt to save the reef.

As they approach the reef again, they notice that several of the fish are dead. The girls jump off the inflatable dinghy with their snorkeling gear on to try and save any fish that are still alive. They come across a fish that is still alive, and move it to land. It becomes clear that pollution from the trawling ship is destroying the delicate balance of the reef.

The adults head out into the sea on a speedboat to try and follow the trawler. The next day they are able to track it down and confront the captain. Blackburn and her father, a powerful businessman, use their influence to have the trawler seized.

With the trawling stopped and the reef recovering from the damage the Thornberrys and their new allies were able to save the beautiful and unique ecosystem for future generations to enjoy. All the animals, including the fish that Eliza and Debbie saved, were able to thrive once again.