Logbooks typically contain detailed notes of events on a ship's voyage. They are updated daily and may include specific dates. Logbooks are maintained by various types of sailors, such as explorers and pirates. The keeper of the log may be the captain of a ship or different individual designated to the task. A logbook may be preserved and passed down after the completion of the voyage, and as such act as an important historical record for future generations.
Zeff kept a log detailing the brave exploits of the Cook Pirates in the Grand Line, which was the pride of himself and his crew. The log survived the Cooking George being shipwreck, and afterwards resided at the Baratie with Zeff. Krieg aimed to steal it after Zeff denied his demand to hand it over to him. Krieg viewed having the log in his possession alongside with a pirate fleet as being able to obtain One Piece.
Mont Blanc Noland's Logbook
Explorer Mont Blanc Noland maintained on a logbook on his adventures 400 years ago. It was later passed down to his descendant Mont Blanc Cricket. The log contains specific dates for events according to the Age of the Sea Circle.
- Sea Circle Calendar 1120, June 21: Noland departs from Vira with his crew. Following the Log Pose, they happen upon a merchant selling an unusual artifact from Skypiea called a "waver".
- Sea Circle Calendar 1122, May 21: Noland's crew lands on Jaya. Noland notes the sound of the South Bird and the golden bell.
- The final entry written on the day of Noland execution: "I saw the gold in the skull's right eye".
Kozuki Oden's Logbook
The samurai Kozuki Oden initially began his journal in Wano Country based on tales he had heard of foreign sailors. However, it later became a proper logbook after Oden managed to leave the country aboard the Moby Dick. It documents Oden's life and adventures with the Whitebeard Pirates and the Roger Pirates. The logbook was salvaged from the burning Oden Castle in Kuri after Oden's execution 20 years ago, and discovered in a river by Yamato. It subsequently remained in Yamato's possession for the next 20 years, before being passed down to Oden's son, Momonosuke.
- The first entries written 39–40 years ago document Oden's travels across Wano and the recruitment of his retainers.
- The entries written 26–30 years ago document Oden's travels with the Whitebeard Pirates.
- An entry written 26 years ago describes Oden's meeting with Gol D. Roger and his recruitment into the Roger Pirates. During the encounter, Roger made an unknown declaration which stunned Oden. Monkey D. Luffy would later make the same declaration to Portgas D. Ace and Sabo.
- The entries written 25–26 years ago document Oden's travels with the Roger Pirates, the journey to Laugh Tale, the disbandment of the crew, and Oden's return to Wano and attack on Kurozumi Orochi.
- "Very important things", which seem to include something about the Will of D.
- A statement regarding the future: Oden predicts that over 20 years in the future, the next generation of powerful pirates will enter the New World and defeat Kaidou.