Medusa is a steel roller coaster located at Six Flags Discovery Kingdom in Vallejo, California. Built by Bolliger & Mabillard, Medusa opened in 2000 as the first floorless roller coaster on the West Coast. The coaster features seven inversions, a 150-foot (46 m)-tall lift hill with a 150-foot (46 m) drop, and the first Sea serpent roll element ever built on a B&M coaster. The ride is the longest coaster in Northern California at 3,937 feet (1,200 m) long and is notable as having one of the largest vertical loops in the world at 128 feet (39 m). It also shares the height record in Northern California with another ride in the same park, The Flash: Vertical Velocity, at 150 feet (46 m) high.