Episode 720 - The Vow of the Pirate Ruler! Luffy's Fight for the Ocean's Tomorrow

Episode 720
The Pirate King’s Promise! Luffy’s Battle for the Future of the Sea
Japanese: 海賊王の約束！ルフィの海の未来をかけた戦い
Kaizoku-Ō no Yakusoku! Rufi no Umi no Mirai o Kaketa Tatakai

The Straw Hats sail through dangerous waters, where they encounter a powerful sea king that almost sinks their ship. After narrowly escaping, they find themselves on a mysterious island filled with hostile inhabitants who are fiercely protective of their land. The crew must fight to defend themselves and uncover the island's hidden secrets.