Strait
A strait is a narrow channel of water between two land areas. A strait connects two bodies of water. Straits often connect two seas. Many straits are economically and strategically important. Straits may be part of important shipping routes. So, someone who controls a strait can control the shipping. Wars have been fought to control them. Although rivers and canals often connect two large lakes or a lake and a sea, they are not straits. Straits are much larger and wider and do not have water running in a single direction.