A great part of One Piece is the world building work put into the series. This means that we get to know certain locations intimately. In that, we come to know its important figures, important historical events and its culture.
This means that, the more the Straw Hats explore, the audience oftentimes becomes very familiar with these locations. This is due to both the fans and the cast habitually learning the information on the different islands, at the same time. One Piece features wacky and whimsical islands, with the most insane weather patterns.
Elbaf is a Kingdom famed for its army of giants. Due to this, it is considered amongst the strongest countries in the world. This country has produced famous pirates such as the Blue Ogre Dorry, the Red Ogre Brogy, captain of the New Giant Pirates, Hajrujdin and the prince of Elbaf, Loki.
Giants are one of the more intriguing races in the One Piece world and, though we have yet to learn much of Elbaf, it remains one of the most interesting islands, one that the Straw Hats must visit in order for Usopp to achieve his dreams.
Dressrosa is the former kingdom of the Warlord of the Sea, Donquixote Doflamingo, and is currently ruled by its rightful monarchy with King Riku Dold III its head. Known as the country of passion, the women are often prone to acts of violence brought on by jealousy. This country is famed for its Corrida Colosseum and the glorious battles that take place within its wall. This is the setting for the Dressrosa arc where we see the Straw Hats save the country from the tyranny of Dressrosa.
Additionally, the people of this country are also fervent believers in fairies, who they believe are responsible for various acts of mischief.
The desert kingdom Alabasta is one of the twenty founding countries of the world government, with their monarchy, the Nefertiti family, being direct blood descendants of the Celestial Dragons.
It is also home to a poneglyph that is believed to hold clues to finding the ancient weapon, Pluton. Pluton is believed to be a battleship strong enough to destroy an island with a single shot. The desert climate of Alabasta was particularly intriguing, given that it was an obstacle the Straw Hats needed to overcome en route to defeating Crocodile and saving the Kingdom.
7 DAWN ISLAND
This island is the birthplace of some of the world’s most notorious criminals such as: the "Most Wanted Man in the World" and leader of the Revolutionary army, Monkey D Dragon, member of the Worst Generation Monkey D Luffy, Chief of Staff of the Revolutionary army, Sabo and the son of the Pirate King and former Whitebeard second division commander, Portgas D Ace.
It's not known why Dawn island produces such legendary figures, but the World Government should definitely look into it. The Goa Kingdom, a corrupt Kingdom known for its grey terminal, is the most famous place on the island, though special credit should be given to Fuusha village as well.
6 TOTTO LAND
Totto Land is ruled by the Emperor of the Sea, Charlotte Linlin, also known as Big Mom. It is an archipelago consisting of 35 different islands, with the main island being Whole Cake Island. It is the Big Mom Pirates’ base of operation and is an almost unbreachable part of the sea. This land was founded by Big Mom, with the aim of transforming it into a utopia for all races of the world.
Due to this, Totto Land is the most diverse country seen in the One Piece world. Despite the great aim of a utopia, the citizens of Totto Land often come under attack from their own Queen, as a result of her fits of hunger. Furthermore, for one to gain residence in this country, a person must pay with their lifespan. Totto Land is known to be a lively place, largely due to the many singing homies that Big Mom likes to create.
5 AMAZON LILY
Amazon Lily is an island commonly offered to as "The Island of Women". It is located in the Calm Belt and is home to the feared, Kuja Pirates. It's ruled over by its Empress, Boa Hancock, the most beautiful woman in the world and a former Warlord of the Sea. This island is known as much for its deadly warriors as it's known for its hatred of men.
Under the constitution of Amazon Lily, no man is allowed to set foot on the island. Even a minor act like that has led to the death of many fearsome pirate crews. Its position in the Calm Belt also means it’s one of the hardest islands to get to, due to the Calm Belt being a natural den for Sea Kings.
4 MARY GEOISE
The Holy Land, Mary Geoise is the land of the Gods, located atop the Redline. Some of the world's most important leaders have taken residence in this land such as: Ruler of the world Im, World Government Commander in Chief, Kong, the Celestial Dragons and the Five Elder Stars.
Mary Geoise is considered to be one of the hardest places to get into, due to it being significantly higher than seas level, the only known way to get to this land is via a gondola at the Redport. Mary Geoise is also known for being the host of the Reverie, a conference held every four years, where rulers of countries affiliated to the world government gather in order to discuss the issues of the world.
3 WANO COUNTRY
Wano is an isolationist country. Not under control of the World Government, it is typically ruled by the Shogun of Wano, with aid from his retainers. Currently, it is under the dual leadership of the Shogun Orochi and the Yonko, Kaido after they killed Kozuki Oden. It's renowned for its strong samurais, who can rival the strongest of fighters.
These people include but are not limited to: Kozuki Oden, Ryuma the Dragon and Ashura Doji. Before Kaido took over, Wano was known as one of the most beautiful countries in the world due to its beautiful Sakura flowers, but much of this beauty has faded under Kaido's rule. Much unlike other countries, Wano uses gold and silver as its currency, lending to its isolationist backgrounds. The citizens of Wano are also kept in the dark about the happenings of the outside world, with little information getting in or out of Wano.
Zou is quite possibly the strangest country on this list,m. It’s not often one comes across a country on the back of a thousand-year-old Elephant. Zunesha is a massive Elephant, cursed to walk around the New World for the rest of its existence. It's not revealed exactly when but, at some point in time, the Mink Tribe settled on its back and built a civilization.
Due to Zou being located on an Elephant, it does not have a magnetic field, meaning log poses can't lock into its location, also meaning Zou is one of the harder islands to come across. This is largely why the Mink Tribe is one of the lesser-seen species in the One Piece world.
1 FISH-MAN ISLAND
Fish-man island is located at 10,000 meters below sea level and is home to the Fish-men and Merfolk. It is constantly suspended in a bubble that allows humans to be able to breathe while on the island. Another interesting thing to note about Fish-man island is that it is constantly illuminated by the Sunlight Tree Eve. Fishman Island is notoriously hard to get to, with only about 30% of ships surviving the journey to the underwater paradise.
Fish-Man island is a beautiful paradise, but is significantly underdeveloped socially, with racism and prejudice often running rampant. Fishman Island is the birthplace of many strong Fish-men, who would later become pirates such as Jimbei and Fisher Tiger. Fish-man island is also home to the ancient weapon, Poseidon, making it one of the most powerful One Piece nations.