Episode 137 - The Power of the Sea King! Luffy’s Greatest Challenge

Episode 137
The Power of the Sea King! Luffy’s Greatest Challenge
Japanese: 海王の力！ルフィの最大の挑戦
Kaiō no Chikara! Rufi no Saidai no Chōsen

The Straw Hats face a series of challenges as they search for more clues about the Void Century. As they investigate an ancient ruin, they come across a group of scholars who have been studying the lost history of the world. Luffy and his crew must protect the scholars from a group of rogue pirates who wish to silence them.