A water slide (also referred to as a flume, water chute, or hydroslide) is a type of slide designed for warm-weather or indoor recreational use at swimming pools or water parks. Water slides differ in their riding method and therefore size. Some slides require riders to sit directly on the slide, or on a raft or tube designed to be used with the slide.

A typical water slide uses a pump system to pump water to the top which is then allowed to freely flow down its surface. The water reduces friction so sliders travel down the slide very quickly. Water slides run into a swimming pool (often called a plunge pool) or a long run-out chute.

Body slides feature no mat or tube, instead having riders sit or lie directly on the surface of the slide. The simplest resemble wet playground slides.

There are a variety of types of body slides including flumes, speed slides, bowls and AquaLoops; the latter three are explained below.

Some slides are designed to be ridden with a tube which typically seats either 2 or 3 riders inline. Similar to a traditional body slide, these slides include many twists and turns and come in a variety of types including bowls, funnels and half-pipes.

The world's longest water slide was a temporary installation in Waimauku, New Zealand, in February 2013. Constructed with a length of 650 metres (2,130 ft), of which 550 metres (1,800 ft) functioned properly. Its creators claimed the previous record holder had a length of ~350 metres (1,150 ft). The slide was to be moved to Action Park in Vernon, New Jersey.^[when?]

The "Waterslide" at Buena Vista Lodge in Costa Rica is a 400 metres (1,300 ft) long water slide where the rider sits directly on the slide, with an inner-tube around their upper body for safety.

The longest multi-person water-coaster (see below) is the 1,763 foot (537 m) long Mammoth at Holiday World in Santa Claus, Indiana.