A body of
water, such as a
river,
canal or
lake, is
navigable if it is deep, wide and slow enough for a
vessel to pass or walk. Preferably there are few obstructions such as rocks or trees to avoid. Bridges must have sufficient clearance. High water speed may make a
channel unnavigable. Waters may be unnavigable because of ice, particularly in winter. Navigability depends on context: A small river may be navigable by smaller craft, such as a
motor boat or a
kayak, but unnavigable by a cruise ship. Shallow rivers may be made navigable by the installation of
locks that increase and regulate water depth, or by
dredging.