Nemesis is an inverted roller coaster located at the Alton Towers amusement park in England. The ride's concept and layout was devised by designer John Wardley. It was manufactured by Bolliger & Mabillard (B&M) and opened in March 1994. It is located in the Forbidden Valley area of the park, adjacent to Galactica, a B&M Flying roller coaster that originally opened in 2002 as Air.
The 716-metre-long (2,349 ft) ride stands 13 metres (43 ft) tall and features a top speed of 80.5 kilometres per hour (50.0 mph). The four-inversion roller coaster was one of the first Bolliger & Mabillard rides to be installed outside of the United States and the first in Europe (as an independent company). The ride has been very well received, consistently ranking highly in industry polls.
It later spawned a sister rollercoaster called Nemesis Inferno, located at Alton Towers sister park, Thorpe Park.
In 1990, Alton Towers added the Thunder Looper roller coaster; the addition was only temporary due to planning restrictions imposed on its installation. The park began planning for a new roller coaster which would open prior the closure of the Thunder Looper. They desired a roller coaster that was big, different and exciting, but they were constrained by the tree-level height limit imposed on the park.
Alton Towers approached Arrow Dynamics for the new roller coaster. The Utah-based company was working on a prototype of a pipeline roller coaster, similar to TOGO's Ultratwister design. John Wardley worked on the design of the ride which was originally to be themed around a secret military facility, codenamed "Secret Weapon 1" (SW1). Due to the design of the ride and the height restriction imposed on the park, SW1 would only have a track length of 300 metres (980 ft). Development of the project was put on hold a short time into the process, due to the financial problems being encountered by Arrow at the time and technical problems with the ride's design. The project was revived a year later under the codename "Secret Weapon 2"; rock blasting was used to clear more space for the larger ride. The project was again abandoned when Wardley rode the prototype, describing it as slow, boring, cumbersome and energy inefficient. The park began to look for an alternative.
Wardley became aware of a new roller coaster design being installed by Bolliger & Mabillard at Six Flags Great America. He subsequently entered into discussions with Six Flags who agreed to privately disclose information about the new ride, in exchange for a similar favour at a later date. Jim Wintrode, the general manager of Six Flags Great America at the time, proposed the concept of an inverted roller coaster that featured inversions. Although Wardley believed this would be impossible, Wintrode worked with Bolliger & Mabillard to develop Batman: The Ride. Wardley rode Batman: The Ride prior to its May 1992 opening and wanted to add a similar ride to Alton Towers.
The inverted roller coaster, then dubbed "Secret Weapon 3", was developed throughout 1992. Wardley and Nick Varney, marketing director of Alton Towers, came up with the name "Nemesis" and pitched a theming concept about an alien creature trapped beneath the park. Tussauds Studios elaborated on this, creating visuals for later promotion. Wardley also worked alongside Stengel Engineering to develop a layout for the ride which was exciting for both riders and non-riders; for example, the final inversion was built at the eye level of an observer.
The £10 million Nemesis officially opened to the public on 19 March 1994, following a soft opening three days prior. It opened as one of the first Bolliger & Mabillard rides to be installed outside of the United States, along with Diavlo at Himeji Central Park, Japan, which opened four months later.
In August 2004, Nemesis gained the Guinness World Record for the "Most Naked People on a Rollercoaster". The ride set the record at 32 riders – the number of seats on a single Nemesis train. It took the record from Thorpe Park's Nemesis Inferno roller coaster which set the record at 28 just three months prior. The ride lost the record in 2010 when 40 naked riders boarded Green Scream Rollercoaster at Adventure Island.
In 2009, Alton Towers received several complaints from nearby residents regarding increased noise levels emitted from the ride. New wheels had to be installed on the two trains before the ride returned to normal operation.