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 roller 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 roller coaster.