Ryker's Island is a New York City jail facility for conventional criminals in Marvel's Spider-Man. It is located in the East River, and has a special branch for dangerous superhuman criminals called the Raft.
Before Marvel's Spider-Man
Spider-Man went to the Raft with Yuri Watanabe when a riot ensued in the vicinity through Otto Octavius' meddling. To stem the riot, Spider-Man fought his way through the facility. Along the way, he broke into the Raft where he fought against Electro, Mister Negative, Rhino, Scorpion and the Vulture.
The group eventually cornered Spider-Man on top of a tower. While Spider-Man was able to briefly hold his own, he was soon overwhelmed once Octavius, now calling himself "Doc Ock", arrived and commanded his team of super-villains finish Spider-Man. As an act of mercy, Octavius allowed Spider-Man to live, with the defeat serving as warning not to cross the group again.
Ryker's Island first appeared in Amazing Spider-Man #4 (September 1963).