Summary:
The Straw Hats are finally ready to enter the Grand Line. Thanks to the map stolen by Buggy, Nami understands that she must reach a point called Reverse Mountain, a mountain crossing the red line where the stream of the four seas diverges into the Great Line. After a terrifying encounter with the Giant Sea Kings of the Tranquil Belt, they finally reach the Red Line Cliffs and a narrow channel entrance that will help them climb Reverse Mountain. Despite the storm and strong currents, they succeed and sail at full speed to the sea.
Luffy thinks that the light from the lighthouse shouldn’t disappear, saying that it’s urgent because they might get lost. Nami reminds Luffy why she is a navigator and remembering the path to the Grand Line is her job. Later, Nami reveals to the rest of the Straw Hats that the entrance to the Grand Line is Reverse Mountain on the Red Line. They are confused because they believe it is impossible to climb the mountain with a ship. Zoro wonders if the map is accurate when Buggy stole it. Luffy, on the other hand, is excited to go to that “magical” mountain. Zoro suggests entering the Grand Line from the south, which shocks Luffy. The captain explains that he has to enter from the mountain because he’s “cool”, much to Nami’s disgust.
Suddenly, the weather calms down, which surprises Nami. He explains that they have to head towards the storm to reach the entrance. They soon realize that they are in the Belt of Calm and that they are in trouble because there is no wind. Nervous about the outcome, Nami orders everyone to row, prompting Usopp to remind her that it’s not a rowboat. Nami explains that the Grand Line is surrounded by two seas. They are in a calm zone, which is a sea without wind and currents.
The ship shakes, confusing everyone that it could be an earthquake. Soon the crew realizes they are surrounded by sea kings. After a moment with the sea kings the crew is back in the storm, Nami reminds Zoro why they have to use the entrance, Zoro now agrees with her.
Nami then understands why they have to head to the mountain and explains that the waves from the four seas gather there to form a current. The current would push the channel of the mountain, and when the water reaches the top of the mountain, it will push back into the Grand Line. The only problem is controlling the rudder to avoid sinking. Luffy, on the other hand, doesn’t get it, and Sanji is impressed with Nami’s navigation skills.
After a while, he sees a large shadow in front of him. They realize it’s a red line surrounded by fog. Sanji and Usopp take the helm. It accidentally breaks when turning the heavy rudder to avoid going off course. Luffy has no choice but to turn into a rubber balloon to avoid crashing into the gate. After a brief moment of tension, the crew is finally back on track and cheering for their success.
Awestruck by the wonders of nature, the crew soon sees the Grand Line.