Lock (water navigation)A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is the chamber itself (usually then called a caisson) that rises and falls. Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level.
NavigabilityA body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel (e.g. boats) to pass safely. Such a navigable water is called a waterway, and is preferably with few obstructions against direct traverse that needed avoiding, such as rocks, reefs or trees. Bridges built over waterways must have sufficient clearance. High flow speed may make a channel unnavigable due to risk of ship collisions. Waters may be unnavigable because of ice, particularly in winter or high-latitude regions.
WatercraftAny vehicle used in or on water as well as underwater, including boats, ships, yachts, hovercraft and submarines, is a watercraft (: watercraft), also known as a water vessel or waterborne vessel. A watercraft usually has a propulsive capability (whether by sail, oar, paddle, or engine) and hence is distinct from a stationary device, such as a pontoon, that merely floats. Most watercraft may be described as either a ship or a boat. However, numerous items, including surfboards, underwater robots, seaplanes and torpedoes, may be considered neither ships nor boats.
Channel (geography)In physical geography, a channel is a type of landform consisting of the outline of a path of relatively shallow and narrow body of water or of other fluids (e.g., lava), most commonly the confine of a river, river delta or strait. The word is generally used to refer to a natural formation of a narrow and is cognate to canal, which is more commonly used to denote an artificial formation. Channels are important for the functionality of ports and other bodies of water used for navigability for shipping.
Caspian SeaThe Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia: east of the Caucasus, west of the broad steppe of Central Asia, south of the fertile plains of Southern Russia in Eastern Europe, and north of the mountainous Iranian Plateau of West Asia. It covers a surface area of (excluding the highly saline lagoon of Garabogazköl to its east), an area approximately equal to that of Japan, with a volume of .
StreamA stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks. The flow of a stream is controlled by three inputs – surface runoff (from precipitation or meltwater), daylighted subterranean water, and surfaced groundwater (spring water).
Ship canalA ship canal is a canal especially intended to accommodate ships used on the oceans, seas, or lakes to which it is connected.sfn|Johnson's|1883|p=1660 Ship canals can be distinguished from barge canals, which are intended to carry barges and other vessels specifically designed for river and/or canal navigation. Ships capable of navigating large bodies of open water typically have more draft, and are higher above the water than vessels for inland navigation.
Cruise shipCruise ships are large passenger ships used mainly for vacationing. Unlike ocean liners, which are used for transport, cruise ships typically embark on round-trip voyages to various ports of call, where passengers may go on tours known as "shore excursions". On "cruises to nowhere" or "nowhere voyages", some cruise ships make two- to three-night round trips without visiting any ports of call. Modern cruise ships tend to have less hull strength, speed, and agility compared to ocean liners.
Body of waterA body of water or waterbody (often spelled water body) is any significant accumulation of water on the surface of Earth or another planet. The term most often refers to oceans, seas, and lakes, but it includes smaller pools of water such as ponds, wetlands, or more rarely, puddles. A body of water does not have to be still or contained; rivers, streams, canals, and other geographical features where water moves from one place to another are also considered bodies of water.
Merchant shipA merchant ship, merchant vessel, trading vessel, or merchantman is a watercraft that transports cargo or carries passengers for hire. This is in contrast to pleasure craft, which are used for personal recreation, and naval ships, which are used for military purposes. They come in myriad sizes and shapes, from inflatable dive boats in Hawaii, to 5,000-passenger casino vessels on the Mississippi River, to tugboats plying New York Harbor, to oil tankers and container ships at major ports, to passenger-carrying submarines in the Caribbean.
