Though it is literally directly under the main seat of power of the World Government, Fishman Island was previously under the protection of Whitebeard, and now Big Mom. It is also notoriously difficult to reach, with only 30% of the ships surviving the journey.
The island is encased in a giant bubble, allowing human visitors to breathe. For World Nobles, it is also one of the few places in the world where their ability to summon a Marine Admiral as they please is not so easy to accomplish.
Main Article: Ryugu Kingdom
- Kingdom Name: Ryugu Kingdom
- Current King: Neptune
- Important People: Otohime (Former Queen), Fukaboshi (First Prince), Ryuboshi (Second Prince), Manboshi (Third Prince), Shirahoshi (Princess), Minister of the Right, Minister of the Left, Fisher Tiger (Former Pirate), Jimbei (Pirate, Former Seven Warlords of the Sea), Joe, Moon.
- Current Affiliations: Big Mom Pirates
- Poneglyph: Yes (Sea Forest)
- Population: Around 5 Million
Fishman Island is an underwater island which dwells 10,000 meters below sea level in a giant hole that goes under the Red Line at the bottom of a deep trench. The island resides in a giant double-layered bubble floating above the sea floor, seemingly filled with about half water and reef and half air. Ryugu Palace rests in a smaller bubble on top of the main island's bubble. It is illuminated by the Sunlight Tree Eve. It serves as an underwater gateway to the New World for those who do not wish to cross over the Red Line above.
Fishman Island is said to be an underwater paradise. Because it is underwater, the only way for a conventional ship to get there is to be coated with a special resin found in the Sabaody Archipelago, and all ships entering the island must undergo a customs inspection.
The island is divided up both by class and by species of creature who lives there. Many of the merfolk live in one section of the island, with the fishmen living in a special district and another section for the richest members of sea society, which includes Pappug. Class also shows itself in various living facilities, where the richer creatures live on the higher floors, closer to the light from the surface, while the poor ones live in the lower, darker areas. The Mermaid Cafe is especially popular in the island.
Even though there is a distinction between fishmen and merfolk, inter-species marriage between the two is allowed. However, donation of blood between humans and fishmen or merfolk is forbidden since ancient times.
Fishman Karate can also be learned here, more specifically in the Fishman Dojo, as stated by Hatchan. This dojo is the pride of Fishman Island.
Amongst Fishman Island, two people are noted to be heroes: Edward Newgate, who declared the island his territory to prevent further abduction of mermaids, and Fisher Tiger, who had many famous adventures and liberated many slaves in Mariejois. Both of them are held at the highest regards within the island, even after their deaths.
The entirety of Fishman Island is ruled by the Ryugu Kingdom, and as such, every landmark falls in the kingdom.