A floating dock is a platform or ramp supported by pontoon

Pontoon (boat)

A pontoon is a flotation device with buoyancy sufficient to float itself as well as a heavy load. A pontoon boat is a flattish boat that relies on pontoons to float. Pontoons may be used on boats, rafts, barges, docks, floatplanes or seaplanes. Pontoons may support a platform, creating a raft. A...

s. It is usually joined to the shore with a ramp that rests upon the dock on rollers, to adjust for the vertical movement of the dock

Dock (maritime)

A dock is a human-made structure or group of structures involved in the handling of boats or ships, usually on or close to a shore.However, the exact meaning varies among different variants of the English language...

. The dock is usually held in place by vertical poles embedded in the soil under the water or by anchored cable

Cable

A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...

s.

Frequently used in marina

Marina

A marina is a dock or basin with moorings and supplies for yachts and small boats.A marina differs from a port in that a marina does not handle large passenger ships or cargo from freighters....

s for small boat

Boat

A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

s, this type of dock maintains a fixed vertical relationship to watercraft

Watercraft

A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

 secured to it, independent of tidal

Tide

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

, river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 or lake

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 elevation. It is less suited for larger craft as the docks cannot support large structures or cranes

Crane (machine)

A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...

.

In some regions of the world, a floating dock is called a pontoon.

PILES(Pontoon Installation + Location Engagement System) are used to secure pontoon and give as little movement as possible.