Chapter 608 is titled "Undersea Paradise".
"Brook Walking Six Dogs (with afros)" requested by P.N. Bachon-san.
The crew breaks through the bubble surrounding Fishman Island but get separated as a result. Luffy, Usopp, Sanji, and Chopper regain consciousness in Keimi's apartment. Fishman Island's culture is further explained. The leader of the New Fishman Pirates orders his crew to bring the Straw Hats to him.
Hammond becomes outraged at the fact that Luffy refused his offer to become a subordinate of the New Fishman Pirates. Luffy makes a face at Hammond, while Chopper pleads with Luffy not to irritate the fishman. Hammond, now angry, states that he cannot let them through and orders the sea lion to attack. However, Usopp, in the energy room of the Thousand Sunny, tells Franky that they are ready to go. Luffy challenges Hammond to a fight but Nami quickly orders for the Coup de Burst to be fired. Franky states that he will settle the score with the sea lion another day. Hammond and his subordinate are surprised at the Coup de Burst. The usage of the Coup de Burst consequently drains the air out of the bubble around the Thousand Sunny, squashing the Straw Hat Pirates into the ship. As the Straw Hats attempt to enter Fishman Island, the bubble coating around the Thousand Sunny is ripped away by the bubble around Fishman Island. Robin quickly explains that the bubble is double layered, and that any ship would fall into the air pocket. The Straw Hats brace for another entry in to the actual Island itself. Water enters the ship (as there is no coating) and all the Straw Hats start to drown. Sanji despairs due to the four Devil Fruit users onboard the ship. Outside, Hammond and his subordinates are puzzled by the "absurd way of entering" Fishman Island. One asks if they should be pursued and Hammond, answers by saying yes. However, Hammond states that it would be annoying if the Neptune Army were to find the Straw Hats first. He then says that they should go back to "Noah" and tell the boss, to say that the one who crushed Arlong's ambition, Luffy, is here.
Meanwhile inside Fishman Island: as Luffy wakes up, he sees five little mermaids surrounding him. He coughs up water, which scares the girls away. Usopp celebrates that Luffy woke up, with Sanji and Chopper sitting beside him. As Luffy wakes up, he recognizes Keimi. Much older now, Keimi is seen cooking, with all the little girls around her waist. Sanji exclaims that she has become more cuter, whilst Keimi herself apologizes for not picking the Straw Hats up, as she remembered the date incorrectly (a month off). Luffy becomes enthralled by the fact they entered Fishman Island. Usopp informs him that the mermaids saved him and that he, Chopper, and Sanji only had woken up recently. It is revealed that they are inside Keimi's house, where half of the inside is water. Luffy is also informed that they had all been split up. Although looking worried, Luffy says that they should all be okay. Sanji agrees, saying that "Bones" (Brook) would be useless in the water (due to the Yomi Yomi no Mi) but that he should be okay since "Robo" (Franky) and "Green" (Zoro) would be there. Keimi brings over soup to warm the four Straw Hats, but exclaims that cold soup would not warm up cold bodies. Usopp assures her that it is okay. The five mermaids return, saying that the clothes are now dry and bring the clothes over. Keimi introduces them as the "Medaka Mermaid Quintuplets". Keimi says that her house is in the "Mermaid Cove" part of the sea floor and that it is a dormitory for the female staff of the town's "Mermaid Cafe" and that there are lots of beautiful mermaids working there as waitresses (including herself). Sanji nearly crumbles at the idea, but soon gets a hold of himself, resisting the nose bleeds. Keimi says that they should go up top now. While at the Underwater Coral Mansion Keimi instructs a turtle elevator to take them up top, she explains that her house is part of an underwater coral mansion. Because her rent is cheap, she lives on the bottom floor, while the top floors are more expensive as they receive more light. The Straw Hats ask about Hatchan. Keimi tells him that he has been recuperating in the "Fishman District" as he is a Fishman. She says that it is a scary place but that she would guide them to it, as Luffy wishes to thank Hatchan face to face. They also ask about Pappug. Keimi informs them that the starfish was now a super famous designer and lives in Gyoverly Hills (Similar to Beverly Hills), a high class district. She invites the Straw Hats to come along to visit as she has to take up clams there anyway. Luffy asks why Keimi is not with him as she was his master. Keimi replies, saying that she "does not fit in". Around them, there are straw like currents, "water roads" which are used to travel. The Straw Hats reach the surface, where there is a mermaid swimming in the sky through a Water Road. A female voice calls out Keimi's name, to Sanji's surprise. A group of beautiful mermaids are shown, all marveling at the Straw Hats's feat of "illegal entry". Keimi introduces them to the mermaids. Sanji starts crying and exclaims in exaggeration that he has found the All Blue. He becomes shocked that a mermaid held his hand and asked him to dance in the sea. However, two mermaids find an intriguing barrel (the one used to contain Caribou). They assume it's treasure or alcohol and note that its locked very tightly. One asks if they should open it.
At Noah, Hammond is seen asking what he should do. A silhouetted face tells him to bring him here (referring to Luffy).
- The Straw Hats enter Fishman Island.
- The "Neptune Army" is mentioned.
- This is the second time that Robin has fallen into water and the first time it showed her completely submerged.
- Keimi is seen for the first time after the timeskip.
- The Medaka Mermaid Quintuplets are introduced.
- Sanji refers to Brook, Zoro, and Franky as "Bones", "Green", and "Robo", respectively, for the first time.
- Two places on Fishman Island is shown: Mermaid Cove and the Fishman District.
- The Straw Hats are once again separated. Luffy, Usopp, Sanji, and Chopper are confirmed to be in the Mermaid District.
- Pappug is revealed to live in "Gyoverly Hills".
- The Fishman District has a large ark called Noah in the background, making a reference to Noah's Ark.
- Sanji finally sees the mermaids he dreamed about and claims that Fishman Island is the "All Blue" (although this most likely just an exaggeration, due to his reaction upon seeing the mermaids).
- The captain of the New Fishman Pirates is shown.
- first appearance