Snowboards are items used by multiple Sonic characters in many Sonic games. They are boards that are built to be used on snow-like terrain. The bobsled is used for the same purpose in the games it appaers in.
In Sonic Triple Trouble, an object known as a "Jet Board" can be used by Sonic in Robotnik Winter Zone. The board allows Sonic to move at high speeds. The board is removed if the player takes damage, or if the player presses both 1 and 2 buttons at the same time.
In Sonic Adventure, Sonic and Tails use snowboards to outrun an avalanche in Ice Cap. Tails also uses his snowboard in Sand Hill. Sonic's is light blue with a snowflake, while Tails' is green and yellow. Metal Sonic also use one when playing as him on the appropriate stages.
Sonic Adventure 2
In Sonic Adventure 2 during the single player stages Sonic rips off some metal from a helicopter to use as a make shift snowboard at the beginning of City Escape or uses a piece of a metal gate he crashed through at the end of Metal Harbor. During Multiplayer all characters in the race type use snowboard model after them in Snowboard Race and the beginning of City Escape.
Sonic the Hedgehog (2006)
In Sonic the Hedgehog (2006) in White Acropolis, Sonic uses a snow board to outrun an avalanche in a similar manner to Sonic Adventure. It is bright blue with orange stripes, but not used for the whole stage. In Crisis City, Sonic uses a piece of debris.
Sonic Rush Adventure
In Sonic Rush Adventure,when the heroes arrive at Blizzard Peaks, Tails gives Sonic and Blaze snowboards. These boards are used for most of act 1. While riding a snowboard, the player automatically moves forward and so the player cannot stop or turn around. They are presumably discarded shortly before the goal. They are also used again in Hidden Island 12. Sonic's is blue with his head emblazed upon it while Blaze's is purple with her head emblazed on it.
In Sonic Adventure, there is a glitch that makes Sonic use his sandboard instead of his snowboard.
In Sonic Generations, Sonic uses a snowboard in City Escape, but in Sonic Adventure 2, he uses a flap he ripped off a helicopter.
The use of a snowboard in City Escape is a development joke back from Ice Cap, where originally Sonic would have used the door that came flying off when Sonic escaped the Flying Battery Zone before the level was put further ahead.