A paddle is a tool used for pushing against liquids, either as a form of propulsion in a boat or as an implement for mixing.

Canoe and kayak paddles

Materials and designs

Paddles commonly used in canoes consist of a wooden, fibreglass, carbon fibre or metal rod (the shaft) with a handle on one end and a rigid sheet (the blade) on the other end. Paddles for use in kayaks are longer, with a blade on each end; they are handled from the middle of the shaft.

Kayak paddles having blades in the same plane (when viewed down the shaft) are called "un-feathered." Paddles with blades in different planes (such as in the image) are called "feathered". Feathered paddles are measured by the degree of feather, such as 30, 45, or even 90 degrees. Many modern paddles are made of two pieces which can be snapped together in either feathered or unfeathered settings. The shaft is normally straight but in some cases a 'crank' is added with the aim of making the paddle more comfortable and reducing the strain on the wrist. Because the kayak paddle is not supported by the boat, paddles made of lighter materials are desired; it is not uncommon for a kayak paddle to be two pounds (32 ounces (910 grams) ) or less and very expensive paddles can be as light as 22 ounces (620 grams). In addition, weight savings are more desirable at the ends of the paddle rather than in the middle.

A spanking paddle is an implement used to strike a person on the buttocks. The act of spanking a person with a paddle is known as "paddling". A paddling may be for punishment (normally of a student at school in the United States), or as an initiation or hazing ritual, or for erotic purposes.

A paddle has two parts: a handle and a blade. Most paddles are designed to be held with one hand, but a giant paddle may be designed to be held with two hands. The blade is typically 3 to 4 inches (100 mm) wide, 1/4 inch thick, and 1 to 3 feet (0.91 m) in length.

In the great majority of cases, the paddle is aimed at the recipient's buttocks; rarely, the back of the thighs might also be targeted.

Paddles for use in schools are made of wood, or occasionally plastic. Paddles used for school punishments may be roughly hewn from commonly available wood. Occasionally, paddles may have holes drilled into them, so there is less air drag when the paddle approaches the buttocks, and produces more sting. The paddles used for fraternity and sorority initiation ceremonies are often professionally made and engraved with organizational symbols and slogans.

A hand paddle is a device worn by swimmers during training. It consists of a plastic plate worn over the swimmer's palm and attached over the back of the swimmer's hand with elastic cords. The plate is often perforated with a pattern of holes.

Handle paddles increase the resistance the hand experiences as it tries to move through the water during the effective part of the arm stroke - the part of the stroke described as the "pull". This gives the swimmer considerably more forward propulsion from the arm stroke that does a naked hand, and affords an enhanced kinesthetic "feel" of the pull. It also enhances the swimmer's feel of the "catch", the phase prior to the pull, where the hand turns from a streamlined position to grasp the water and begin the pull. If the hand catches or pulls at an incorrect angle, the increased resistance afforded by the hand paddle will exacerbate the result twisting moment, making the defect clearer to the swimmer. The considerably increased load imposed by the hand paddle on the arm and shoulder can, however, lead to pain and an increased risk of injury, so coaches advise only limited use of paddles and that use be discontinued if the swimmer feels shoulder pain.