Cinnabar Island is an island in the First Generation that has the Seventh gym on it. There are two ways to get to it, one being going to Pallet Town and surfing south, the other is by going through the Seafoam Islands. The easier way is by going to Pallet Town, but the way the game designers made the game, you are supposed to go through the Seafoam Islands. There is also the lab to get your fossil from Mt. Moon turned into a pokemon, and the Old Amber from the Museum in the town with the first gym. To open the doors of the seventh gym you must go through the Abandoned Mansion on Cinnabar to get the Key on the bottom floor. There is also the Missingno. glitch in Red, Blue, and Yellow that if you surf up and down the right side of Cinnabar Island there will be level 150+ pokemon or the rare missingno. that will clone the sixth item down in your bag. Do not catch Missingno. though because, since it is a glitch, it will corrupt your game if caught. There is a Pokemon Center and a PokeMart in Cinnabar, just like every other city with a gym. The Cinnabar Pokemart sells Great Balls, Ultra Balls, Burn Heals, Antidotes, Ice Heals, Super Potions, and Max Potions.
Related ThreadsCan't find Bill on Cinnabar Island, help please? - last post by @ Oct 14, 2011
Cinnabar Island & Safari Zone - last post by @ May 30, 2009
A glitched trainers? on a cinnabar island coast? - last post by @ Jun 21, 2010
i really need help on cinnabar islands - last post by @ Dec 29, 2008
Help on finding key cinnabar island gym - last post by @ Oct 25, 2007