Mandrill Mayhem is a launched, steel shuttle wing coaster located at Chessington World of Adventures in Chessington, United Kingdom. The ride was designed by Swiss rollercoaster manufacturers Bolliger & Mabillard, and is located in the World of Jumanji section of the park, themed to the Jumanji film and book franchise. A consultation for the ride took place in May 2021, and the coaster opened two years later on the 15th May 2023. The last row faces backwards.

The 1,247-foot-long (380 m) ride stands 66 feet (20 m) tall and features one inversion – an inline twist, two LSM launches, a junior scorpion tail spike and a 405° spiral rollback. Riders experience speeds of up to 45 mph (72 km/h). The trains are stylized as mandrill monkeys holding the riders in their arms. The ride features a single train with 7 cars. Riders are arranged 4 across in a single row for a total of 28 riders, making for a theoretical capacity of 840 guests per hour.

Guests between 1.2m and 1.3m must be accompanied by an adult over the age of 16, while those a minimum height of 1.3m can ride alone. The ride sits alongside two other attractions, manufactured by the Italian SBF Visa Group, Ostrich Stampede (a ‘Jump & Smile’ model) and Mamba Strike (a ‘Miami’ flat ride).

Mandrill Mayhem is the only Bolliger & Mabillard installation in the world that does not form a complete circuit.

Chessington opened an online, two-week consultation for the ride and the surrounding area on the 17th May 2021, and held two in-person consultation in the hotel's conference centre. Plans were then submitted to Kingston Council in August 2021, with the park citing they “must respond decisively” following the COVID-19 pandemic, with an attraction that “excites visitors and generates interest within the industry”. Plans were approved for the area towards the end of January 2022, starting a 15-month build process.

The ride and the surrounding area were officially announced to themed to the Jumanji franchise in August 2022, with trademarks submitted for the attractions in December of that year. Merlin Magic Making's lead creative, John Burton designed the area. The land, including Mandrill Mayhem had a press launch on the 13th May 2023, by Merlin Entertainment's CEO, Scott O' Neil, who said the themed land was his company's “most expansive and exciting yet”. The World of Jumanji is said to have cost £17 million, serving as the park's single biggest investment since opening.

The attraction officially opened on the 15th May 2023, with a virtual queuing system due to uncertainty around the ride's capacity to manage a conventional queue. Six Jumanji themed bedrooms complimented the area, in the park's Safari Hotel, following a deal between Merlin Entertainments and Sony covering both Europe and North America, which includes attractions, rides, lands, retail outlets and themed hotel rooms.

Mandrill Mayhem is the first-ever shuttle wing coaster built by Bolliger & Mabillard. The train is lightly launched backwards out of the station, entering into a banked turn before climbing 65 feet (20 metres) up a ‘beyond-vertical’ spike, known as a ‘Junior Scorpion Tail’, due to its shape; despite being at an angle slightly greater than 90°, this element is not considered an inversion. Rather, as the train ascends and briefly stops at the top, riders will momentarily face the ground. At the top of the spike, the train's gravity pulls it back down, passing again through the station, where it receives its second launch (achieving a maximum speed of 45 mph) before going through an in-line twist, serving as the park's first actual inversion on a roller coaster. This is followed by a 405° spiral rollback, going around the area's central theming feature, the mountain sculpture called ‘Jaguar Shrine’, a rock in the shape of a large feline predator's head. The train then reaches a brake at the top, rolling backwards and traversing the layout once again, before reentering and finishing at the station.

• Mandrill Mayhem at Chessington World Of Adventures
• Mandrill Mayhem at Chessington Buzz