The Warship Island Arc, sometimes referred to as the Apis Arc, is a story arc in the anime One Piece. It is the first story arc of the series not to be based on any content from the manga by Eiichiro Oda, making it the first filler arc. It was left out of the 4Kids dub for an unspecified reason. This arc takes place just after Luffy receives his bounty of 30,000,000Beli at the end of the East Blue Saga, and before the Straw Hat Pirates enter the Grand Line.
The Straw Hats find a young girl named Apis floating in the ocean. They find that she has escaped from Marine Branch 8 and is running from Commodore Nelson. The Straw Hats agree to return her back to Warship Island, and they are soon attacked by Branch 8. After escaping from the Marines, the Straw Hats realize that they are in the Calm Belt where they find large sea kings. Then, narrowly escaping the Sea Kings and the Calm Belts, they continue on their course to Warship Island.
After reaching Warship Island, they find out that Apis has a Devil Fruit ability that allows her to talk to animals, and she has used it to befriend a dying Sennenryu, a type of dragon species thought to be extinct. She wants to return this Sennenryu to his homeland, but they run into two problems: A Marine fleet is after the dragon also, because it can be used to make a powerful, and valuable, medicine. Their commander (Commodore Nelson Royale), has hired the mercenary Eric (A Devil Fruit user with claws so sharp, that he can cut the air) to help him get the Sennenryu, but Eric has his own agenda, and wishes to keep it for himself. They do not know where the Sennenryu's homeland is. This arc chronicles the Straw Hats' efforts to return the Sennenryu to his home, make Apis happy, and stay out of Eric's way.