Chapter 605

Chapter 605 is called "The kraken and the pirates".

Short summary
Luffy and Co. arrive at the Kraken and foolishly aim to tame it. Usopp is startled by the Kraken and try to convince Luffy to give up his ridiculous idea with Chopper mentioning that it has been alive for hundreds of years, being considered almost "mythological". Coribu's ship then arrives from behind, and is annihilated by the Kraken. Luffy, Sanji, and Zoro then get lifesuits named "Barefoot Coating" and set out to tame the beast. While the crew is dodging the Kraken, Luffy enters Gear 3 and hardens his enormous fist with the "Color of Armaments" Haki, while Sanji and Zoro run interference with their respective strengths. Luffy blows away the Kraken with his gigantic fist, and a shark pops out from under the Kraken. The Crew, with Luffy, Sanji, and Zoro on the outside, get sucked into the trench in end up in the Deep Sea, considered the "Underworld" of the sea.

Chapter notes

 * This is the second time that some of the Straw Hat Pirates go diving outside the ship, the first during the Jaya Arc. Coincidentally they are the same people: Luffy, Zoro and Sanji.
 * This is also the second time that someone exits from the mouth of a sea creature that has just been defeated with a punch, the first being Pappug and Keimi in Hatchan's cover story.