Chapter 606 is titled "Adventure in the Ocean Depths".
"Robin Reads a Book Under a Tree with a Canary-like Bird Singing on it" requested by P.N. Yuuki-san.
The crew continue their journey down. Usopp is seen calling for Luffy, Zoro and Sanji. The crew see jellyfish around the ship and one of them sticks their tentacle through the coating. Chopper tries to touch it, but is warned away by Robin. Franky uses the Coup de Burst to avoid a Sea King. Brook realizes that Caribou is missing. Caribou is shortly found and caught by Franky who locks him into a barrel. They are attacked by a Sea Devil only to be saved by captain Vander Decken. They turn on the Straw Hat Pirates realizing they are enemies; Luffy, Zoro, and Sanji come to their rescue having tamed the Kraken, whom Luffy named Surume.
The Straw Hats still on board the Sunny are looking for Luffy, Zoro, and Sanji in the dark depths of the Deep Sea. It is hard to search the water due to it being so dark. Even the Sunny's headlight beams could not penetrate that far into the water. The ship is then surrounded by a school of enormous jellyfish. One of the jellyfish stuck one of its tentacles through the coating bubble. Chopper tries to touch it but Robin yells at him not to touch it, as they are poisonous. Franky uses a Coup de Burst just as a giant fish bites down on the jellyfish. Brook notices that the Coup de Burst lowered the air level on the ship somewhat. Right after he says this, the large fish turns onto its back, killed from the nerve toxin inside the jellyfish. Chopper notices that there are a lot of fish with white eyes. Brook comments that the eyes on a lot of fish at this level are vestigial, making them unable to see at all. Usopp and Chopper take advantage of this and start teasing the large fish. Robin then states that there are also fish whose eyes have evolved to see in the darkness. Resuming the search, Brook notices that Caribou had escaped from the ropes that were holding him. No one had seen Caribou since they had reached the Deep Sea, suggesting he might have been thrown overboard. Caribou is really hiding in a barrel nearby as everyone realizes he could be hiding anywhere on the ship and they need to be even more on guard. Caribou considers sneaking into the girls' room, saying he had been planning to do so. He seemed please that the Monster Trio is gone, thinking/saying they all must be dead by now. He was disappointed that he could not take Luffy's head, but figured the heads of the rest of the crew would be just as good. He will wait until the instant they land at Fish-Man Island to attack.
While he is thinking all this out. Franky notices him in the barrel. He forces the lid of the barrel down and seals the barrel with ropes and by bolting large metal holding plates along the sides of both ends of the barrel. Franky realizes that Caribou had let himself get hit by Sanji earlier in order to hide his mud-like Logia powers. Franky concludes that the crew would have been in trouble if Caribou wasn't such an idiot. As Franky walks away, Caribou, from the barrel, begs Franky to let him out, saying he would become Franky's slave if he did, calling him "Mister Trunks". Franky then notices that something was bothering Chopper and asks him what is wrong. Chopper says it has become really hot, and Usopp agrees. The crew then notices that they are heading into a cloud of smoke. Nami realizes that smoke under water, coupled with hydrothermal mineral deposits could only mean they were in a Deep Sea volcanic region. The Sunny is right above the mouths of several volcanoes. Franky realizes that if the volcanoes erupt, they would be killed instantly and proceeds to steer the ship away from the volcanoes. The crew is then chased by carnivorous tube-worms, a noppera crab, and several other creatures. Chopper complains that he cannot go on living and misses Luffy, Zoro, and Sanji, saying he waited two years to see them and when he finally does, they disappear. Chopper then notices a light in the distance, wondering if they had reached Fish-Man Island. Nami says no, as they still have 3000 meters to go. Franky uses his Nipple Lights to ask in Morse Code "W-H-O-A-R-E-Y-O-U-?" The light turns out to belong to a giant angler fish. The fish tries to eat the ship, but is stopped by a giant humanoid creature. Usopp identifies it as an umibozu, a sea giant (sea devil). The giant punches the angler fish, whose name is Ankoro, saying it was not supposed to attack ships and that captain Vander Decken would be mad at them. Brook then hears someone singing. A ghostly ship approaches from behind the giant. The ship is old and parts of it are worn. Everyone was shocked at this sight, even Brook, which prompted Usopp to say that Brook shouldn't be surprised.
Brook identifies the ship as "The real thing", the Flying Dutchman. He then proceeded to give the history of the ship and its captain. It is called "The ship that should not be". The story dates back hundreds of years. On a stormy day, a captain became deranged and started throwing his crew overboard, killing all of them. The captain's name was Vander Decken. He incurred the wrath of God, and was doomed to an eternity of wandering the sea, forbidden to ever make port. That ship is the very same ship they see before them, the cursed ship of Vander Decken.
Vander Decken, whose whole body was shadowed except his arm, told the angler fish and the giant, whose name is Wadatsumi, that they would not get treasure if they ate the ship. He tells them to "knock it down." Someone yelled for Franky to use Coup de Burst, but Franky said they cannot since they ran out of fuel just then. They are saved, when the kraken shows up out of nowhere and punches Wadatsumi in the chin. Everyone on the ship is surprised to see it again. Vander Decken calls the Kraken "Monster of the Arctic". The Kraken continues to beat up the giant until ordered by Luffy to stop, which it did. Everyone is relieved to see that Luffy, Zoro, and Sanji are alive, all three are in the same bubble. Wadatsumi is unconscious with large bruises. Luffy tells them that his and Sanji's bubbles broke, so they all had to share Zoro's. Luffy did not like it in the cramped bubble. He sprawls out on the deck of the ship, happy for so much room. Franky notes how much vitality they all have. Nami asks if they actually tamed the kraken. Luffy says he is going to turn the kraken, who he named Surume, into a top-notch navigator as Surume places Thousand Sunny on his head. Usopp says they should be careful the ship is not crushed. Everyone then hears a rumbling sound coming from one of the volcanoes. Vander Decken's crew alerts him that there is trouble, as Nami realizes the volcano is about to erupt.
- Robin yells at Chopper, showing concern (first time) for the welfare of another crew member's safety, instead of suggesting the worst possible way they could die.
- Franky shows that he has various tools stored in his forearms.
- Caribou's Devil Fruit ability is confirmed to be related to mud.
- Franky locks up Caribou inside a barrel that he was hiding in (even with a Logia-type Devil Fruit power).
- An underwater giant named Wadatsumi is introduced.
- The legend of Vander Decken and the Flying Dutchman is revealed.
- It is shown that the Kraken has been tamed and named Surume by Luffy.
- Luffy, Zoro, and Sanji are once again reunited with the rest of the Straw Hat Pirates.
- member joining crew
- first apparition
4: name given/name revealed