Known as "The Great Underwater Prison," Impel Down is the largest prison in the One Piece world where criminals of all sorts were imprisoned, including the most heinous of pirates. This prison is a part of the three greatest strongholds of the World Government, with Enies Lobby and New Marineford being the other two.

Some of the most powerful pirates in the series found their way to Impel Down and during the Great Prison Outbreak shortly before the Summit War, most of them broke out. Here are the 10 strongest pirates to ever get imprisoned in Impel Down.

10 Avalo Pizarro

Famed as the Corrupt King throughout the entirety of the South Blue, Avalo Pizarro was caught and brought to Impel Down at an unknown time. During Blackbeard's attack on the prison, he was finally freed and he ended up joining his crew.

After Blackbeard's rise to the Yonko spot, Pizarro came to be known as the leader of the Fourth ship of Blackbeard, which goes to show that the Yonko has a lot of trust in him and his abilities.

9 Catarina Devon

Devon, also known by the epithet of Crescent Moon Hunter, was locked up in Impel Down Level 6, just like Avalo Pizarro. She's known to be the most dangerous female pirate in the history of One Piece, which solidifies her reputation as one of the strongest in the series.

Devon is the captain of the sixth ship of the Blackbeard Pirates. She's also a user of the Mythical Zoan Inu Inu no Mi, Model: Kyubi no Kitsune which allows her to transform into a nine-tailed fox and take on the appearance of anyone.

8 Crocodile

Crocodile One Piece

One of the former Shichibukai, Crocodile was arrested and thrown in Impel Down after the events of the Alabasta Saga of One Piece. Being a tremendously dangerous pirate, Crocodile was locked up in level 6 of the prison.

With the powers of the Logia type Suna Suna no Mi, Crocodile was a massive threat to nearly anyone who stood in his path. It goes without saying that he's among the strongest to have been imprisoned in Impel Down.

7 Luffy

One Piece Luffy Versus Magellan

Monkey D. Luffy broke into Impel Down to save his brother, Portgas D. Ace from being executed at the hands of the World Government. After facing Magellan, Luffy was tossed into Impel Down level 5 and later sentenced to a level 6 sentence.

Thanks to help from Bon Clay and Ivankov, Luffy ended up recovering from Magellan's poison quite quickly and broke out of the prison successfully, leading a massive army of prisoners with him.

6 Jinbe

Also known as Knight of the Sea, Jinbe is a former Shichibukai, just like Crocodile. He was thrown in Impel Down upon refusing to ally with the World Government for the Summit War.

With a bounty of 438 million berries, Jinbe is an incredible pirate who is skilled in the ways of Fishman Karate, and also is an adept user of Haki. Evidently, a man of his stature was locked up in Impel Down level 6 as well and he broke out thanks to help from Luffy.

5 Shiryu

Also known as Shiryu of the Rain, he was the former Head Jailer of Impel Down who was locked up due to massacring prisoners for fun. In terms of strength, Shiryu was said to be on par with Magellan, the Warden of the prison.

After Blackbeard's attack on Impel Down, Shiryu decided to abandon his job and join the Blackbeard Pirates.

4 Portgas D. Ace

Luffy - One Piece

Portgas D. Ace was the Second Division Commander of the Whitebeard Pirates and one of Whitebeard's strongest men. Ace was defeated by Blackbeard and handed over to the Navy, which eventually boiled down to the Summit War.

He's known to be the most troublesome pirate to be ever imprisoned in Impel Down. His strength as the Second Division Commander of the Whitebeard Pirates is enough to see him take this spot on the list.

3 Donquixote Doflamingo

Renowned as the Heavenly Demon, Doflamingo is the former Captain of the Donquixote Pirates and one of the former Shichibukai as well. After being defeated by Monkey D. Luffy, Doflamingo was thrown in Impel Down level 6.

Being a proficient user of all Haki types, along with having the Awakened powers of the Ito Ito no Mi, Doflamingo is strong enough to take the 3rd spot on the list.

2 Douglas Bullet

Also known as the Demon Heir, Douglas Bullet was once a member of the Roger Pirates who left the crew just after serving on it for 3 years. After Roger's capture, Bullet was taken down and thrown into Impel Down, where he built up his strength and awakened his Devil Fruit.

His powers were said to be on par with Rayleigh back in the day and in the current timeline, around the level of a Yonko.

1 Shiki

Shiki is the strongest known pirate to ever be imprisoned in Impel Down. His strength was comparable to the likes of Roger and Whitebeard, making him an elite pirate of the sea.

The Golden Lion attacked Marineford after news of Roger's execution broke out and took on Sengoku, Garp, along with several other Marines all by himself. After destroying half of Marineford, Shiki was finally imprisoned in Impel Down.

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