Hydra the Revenge (also known as Hydra) is a steel floorless roller coaster at Dorney Park & Wildwater Kingdom in South Whitehall Township, Pennsylvania (USA). It was built where the wooden roller coaster Hercules stood, which was closed for demolition at the end of the park's 2003 season. Its name is actually in honor of the coaster that stood in Hydra's spot: Hercules battled the Hydra in Greek Mythology
Hydra is the second roller coaster in the United States with an inversion before the lift hill, after Red Devil at Ghost Town in the Sky. This inversion is a heartline roll, and is popularly known as the "Jojo roll" pictured here.