Two adults died and 14 people, including six children, were injured after falling from the ‘world’s longest water slide’. Source
Accidents
Theme parks and roller coasters are statistically very, very, very safe. Out of the millions of people who ride the thousands of rides every year, there are only a small handful of incidents. You are statistically more likely to be involved in an accident driving to an amusement park than having one at a park. The rarity of accidents is one reason why the media report them, similar to plane crashes.
Every important element of a ride is inspected on a regular basis and every ride is tested every day without passengers before it opens. A ride might not open, or a safety system might activate, if there is an imperfection. For theme parks to operate, they must obtain insurance and one stipulation is their rides are frequently inspected and signed off by a strict Health & Safety governing body. Every theme park does what they can to prevent accidents because the negative press would be bad for business.
Having said all that, theme park accidents still happen…
Ferris Wheel, Grote Market, Bergen, Belgium
A 38-year-old ride owner died in a fall while dismantling his 115 foot (35 m) tall Ferris Wheel at the local spring market. Source
Star Flyer, Parko Paliatso, Ayia Napa, Cyprus
A 44-year-old mother and her 7-year-old son were ejected from the 180 foot (55 m) tall aerial chair-swing when parts of their seat tore off, due to their chair hitting a nearby ride after reportedly going too fast on too wide an angle. The boy suffered an exposed fracture on his right leg, while his mother lacerated her left knee, broke her right hand and suffered concussion. Source
Air Race, Brighton Pier, England, UK
El Loco, Adventuredome, Las Vegas, Nevada, USA
Octopus, New Saniro Dream Paradise, Veyangoda, Sri Lanka
A 13-year-old girl and her 47-year-old mother died when the car they sat in detached from its rotating arm. Source
Alpen Coaster, Dom, Hamburg, Germany
A 44-year-old employee working near a curve of the traveling Schwarzkopf Wildcat coaster died after he was hit by the train during testing two days before the opening of the annual Winterdom funfair. Source (in German)
Hyperion, Energylandia, Zator, Malopolskie, Poland
A 37-year-old employee working at the Intamin mega coaster died when he reached for a phone that a guest dropped and one of the trains struck him. Source (in Polish)
Twister, Virgin of Santa Ana Fair, Pacueco, Mexico
A four-year-old girl died after falling 32 feet (10 m) from the Sartori Rides magic carpet style ride. The child sat in her mother’s lap when the toddler slipped from her arms and fell from the moving ride to the pavement below. Source (in Spanish)
Ride the Ducks, Branson, Missouri, USA
A duck boat carrying 31 people took on too much water and capsized during stormy weather, killing 17 people. Nine of the victims were family members, including an infant. Winds at the time were blowing as hard as 65 mph (104.5 km/h), according to the National Weather Service. Source (with video news report)