Extreme slides or speed slides are straight, with a near vertical drop in the middle designed to give the rider the most possible speed. These are called "plunge" or "plummet" slides, and are one of the most fearsome slides due to their height. They can accelerate people up to an average of 55 miles per hour. The tallest plummet slide in the world is Spacemaker at 42 meters (137.8 feet), which can bring riders up to 100 km/h (62.1 mp/h), located at Aqualandia, a water park at Jesolo Beach in northern Italy. This slide requires riders to sit on a raft, and thus does not fall into the same category as the highest single rider/raft-free water slide Insano at 41 meters (135 feet), which can bring riders up to 65.24 mph, located at Porto das Dunas Beach, a part of the Beach Park Resort in Fortaleza, Brazil.
An innovative example of an extreme slide would be the Sidewinder, produced by a Calgary,AB firm, "Waterfun Products". The Sidewinder is a unique combination wet/dry ride that propels riders from side-to-side in a single, double or triple person rafts. Water spray jets provide a frictionless surface on a giant u-shaped slide as rafts are channelled effortlessly to the bottom. The steep entry on to the slide surface provides riders with the thrill of "free falling".