
Reverse Mountain is the entrance to the Grand Line. What await the Straw Hats are impossible water currents, a giant whale, and dubious people going by codenames.

Following a near disaster in the Calm Belt, the Straw Hats take a wild ride up and down a mountain… and are promptly swallowed by a giant whale!

After learning of Laboon the whale's plight, Luffy comes up with a solution befitting his style. As thanks, Crocus reveals that navigating the Grand Line will not be as simple as following a compass or relying on currents and wind.