Jinbe is a whale shark fishman who was the second captain of the Sunny Pirates after Fisher Tiger, and who became a Shichibukai eight years ago. Jinbe's name comes from jinbei-zame (甚平鮫), which means "whale shark" in Japanese. His epithet, Kaikyou would normally translate into "Strait" or "Channel." However since the kanji for it is written as (海侠の) and not (海峡の), the kyou part (侠) of it comes from (任侠), a honorific used when addressing a high ranking yakuza member, thus making his epithet a Japanese pun.

During the Impel Down arc Jinbei refused to go to war with Whitebeard, getting himself locked up in Impel Down in the same cell as Ace. He then teams up with Luffy and the others to rescue Ace, and decided to give up his position as a Shichibukai.
(Source: One Piece Wiki)