Sea kayaking at Wilsons Promontory in Victoria, Australia

Kayaking is the use of a kayak for moving across water. Kayaking and canoeing are also known as paddling. Kayaking is distinguished from canoeing by the sitting position of the paddler and the number of blades on the paddle. A kayak is defined by the International Canoe Federation (the world sanctioning body) as a boat where the paddler faces forward, legs in front, using a double-bladed paddle. Most kayaks have closed decks, although "sit-on-top" kayaks are growing in popularity, as are inflatable kayaks which come without decks but which have air chambers surrounding the boat.

Whitewater kayaking involves taking a kayak down rapids, weirs and waterfalls. Sea kayaking, also referred to as ocean kayaking or touring, involves taking kayaks out on to the ocean or other open water such as a lake. It can involve short paddles with a return to the starting point (or "put-in"), or expeditions covering many miles and days. Kayaking of all kinds has become more popular through the 1990s and early 21st century.

Kayaking at Great Falls, Virginia.

Kayaks are classified by their use. There are eight primary classifications: polo, slalom, whitewater, surf, touring/expedition, light touring/day tripping, sprint/racing and general recreation. From these primary classifications stem many sub-classes. For example, a fishing kayak is simply a general-recreation kayak outfitted with accessories that make it easier from which to fish. A creek kayak is a certain type of whitewater kayak, designed to handle narrow gully type rivers and falls. Also within these classifications are many levels of performance which further separate the individual models. In other words, not all touring kayaks handle the same.

Kayaks and canoes are also classified by their design and the materials from which they are made. Kayaks can have hard or soft chines which require different types of handling. Each design has its specific advantage, including performance, maneuverability, stability, and paddling style. Kayaks can be made of metal, fiberglass, wood, plastic, fabrics, and inflatable fabrics such as PVC or rubber. Each material also has its specific advantage, including strength, durability, portability, flexibility, resistance to UV, and storage requirements. For example, Wooden kayaks can be created from kits or built by hand, but they are heavy to transport. Inflatable kayaks, made from lightweight fabric, can be dried, deflated, and stored in a closet.

Glowworm Kayaking at Waimarino Adventure Park

There are several major configurations of kayaks. "Sit on tops", as the name suggests, involve sitting on top of the kayak in an open area. "Cockpit style" involves sitting with the legs and hips inside the kayak hull with a "spray deck" or "spray skirt" that creates a water resistant seal around the waist. "Inflatables" are a hybrid of the two previous configurations, these boats have an open deck, but the paddler sits below the level of the deck. "Tandems" are configured for multiple paddlers, in contrast to the single person designs featured by most kayaks. Tandems can be used by two or even three paddlers. How a kayak is configured has nothing to do with its classification. All configurations are represented in each of the five primary classifications.

Because of their range and adaptability, kayaks can be useful for other outdoor activities such as diving, fishing, wilderness exploration and search and rescue during floods.