An isthmus is a narrow strip of land that connects two larger landmasses and separates two bodies of water. 
 
Isthmuses have been strategic locations for centuries. They are natural sites for ports and canals linking terrestrial and aquatic trade routes. Isthmuses are also key sites for communications and cultural exchange, as well as military outposts.
 
Isthmuses
 
The Isthmus of Panama in Panama links the continents of North and South America, and separates the Pacific and Atlantic Oceans. The Panama Canal stretches 77 kilometers (48 miles) across the isthmus, and allows cargo ships to travel from eastern North America to western North America without having to go around South America. The Panama Canal revolutionized shipping and travel in the 20th century, allowing for faster and more efficient transportation of goods and people.
 
The Isthmus of Suez in eastern Egypt connects the continents of Africa and Asia, and separates the Mediterranean and Red Seas. The Suez Canal is 192 kilometers (119 miles) long and allows cargo ships to travel between Europe, North Africa, western Asia (via the Mediterranean Sea in the north) and eastern and southern Asia without having to go around Africa. The Suez Canal facilitated trade and travel in the 19th century, and continues to define the oil trade today.
 
The city of Seattle, Washington, is located on an isthmus between the Puget Sound (part of the Pacific Ocean) and Lake Washington. The region has been continuously inhabited for more than 4,000 years. The earliest settlers of the area were the Duabish, who settled near the ocean, and the Hachuabish, who settled near the freshwater lake. European settlers, who quickly saw the isthmus' potential for trade along the west coast of North America as well as across the Pacific, collectively referred to these Native Americans as the Duwamish.
 
Tombolos
 
Tombolos are a type of isthmus. A tombolo forms as tides and waves create a thin strip of land between a coastal island and the mainland. The island connected to the mainland in a tombolo is called a tied island. (The built-up sandbar "ties" the island to the mainland.)
 
Mount Maunganui, New Zealand, is a tombolo town located on a sandbar connecting the volcanic island of Mauao to the mainland. Mauao is an extinct volcano, and is a popular spot for hiking and sightseeing the local beaches. Those beaches offer diverse opportunities due to the tombolo formation. Beaches on the side of Mount Maunganui's isthmus facing Tauranga Harbor are calm and protected. Beaches on the other side of Mount Maunganui face the open ocean (the Pacific), with dramatic waves that are popular with surfers.
 
Perhaps the most famous tombolo is the Rock of Gibraltar, a tied island narrowly connected to the southwestern tip of Europe's Iberian Peninsula. The Rock of Gibraltar is the northern part of the "Pillars of Hercules," which form the narrow western entrance to the Mediterranean Sea. This strategic location has made the Rock of Gibraltar a key site for traders and explorers since the Phoenicians. Today, the Rock of Gibraltar borders Spain, but is part of the British territory of Gibraltar.
isthmus
Storms may make isthmuses like this one dangerous places to live.

Passing Through
It takes ships about 8-10 hours to cross the Isthmus of Panama through the Panama Canal. About 14,000 ships make the crossing between the Atlantic and Pacific Oceans every year.

aquatic
Adjective

having to do with water.

Noun

narrow strip of land that lies along a body of water.

border
Verb

to exist on the edge of a boundary.

canal
Noun

artificial waterway.

cargo
Noun

goods carried by a ship, plane, or other vehicle.

city
Noun

large settlement with a high population density.

Noun

edge of land along the sea or other large body of water.

collective
Adjective

combined or unified.

communication
Noun

sharing of information and ideas.

Noun

one of the seven main land masses on Earth.

define
Verb

to identify or associate with.

diverse
Adjective

varied or having many different types.

efficient
Adjective

performing a task with skill and minimal waste.

extinct volcano
Noun

volcano that will no longer erupt.

facilitate
Verb

to help or make easier.

Noun

part of a body of water deep enough for ships to dock.

inhabit
Verb

to live in a specific place.

Noun

narrow strip of land connecting two larger land masses.

landmass
Noun

large area of land.

Noun

armed forces.

Noun

large body of salt water that covers most of the Earth.

oil
Noun

fossil fuel formed from the remains of marine plants and animals. Also known as petroleum or crude oil.

open ocean
Noun

area of the ocean that does not border land.

outpost
Noun

settlement or station located in a remote area.

Noun

piece of land jutting into a body of water.

Noun

place on a body of water where ships can tie up or dock and load and unload cargo.

potential
Noun

possibility.

Noun

any area on Earth with one or more common characteristics. Regions are the basic units of geography.

revolutionize
Verb

to completely change a process or way of doing something.

sandbar
Noun

underwater or low-lying mound of sand formed by tides, waves, or currents.

Noun

large part of the ocean enclosed or partly enclosed by land.

settler
Noun

person who migrates and establishes a residence in a largely unpopulated area.

shipping
Noun

transportation of goods, usually by large boat.

site
Noun

specific place where something is located.

sound
Noun

body of water, larger than a bay, partially surrounded by land.

strategic
Adjective

important part of a place or plan.

terrestrial
Adjective

having to do with the Earth or dry land.

Noun

land an animal, human, or government protects from intruders.

Noun

rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun.

tied island
Noun

island permanently linked to the mainland through a narrow strip of sand built up through the action of waves and tides.

tombolo
Noun

coastal landform created as waves and tides create a narrow, permanent isthmus between a coastal island and the mainland.

trade route
Noun

path followed by merchants or explorers to exchange goods and services.

transportation
Noun

movement of people or goods from one place to another.

volcanic island
Noun

land formed by a volcano rising from the ocean floor.

wave
Noun

moving swell on the surface of water.