Simplified diagram

An isthmus is a narrow strip of land, bordered on two sides by water, and connects two larger land masses. The term is pronounced "ISS-mus" with a silent "th". The plural form can either be isthmuses or isthmi. A land bridge may be an isthmus.

The most famous isthmus is Panama, which connects North America and South America. Other isthmuses include:

• the first isthmus to be called an isthmus, Isthmus of Corinth, in Greece
• the isthmus of Dubrovnik - today's Stradun , (main center street), which connected Laus and Dub into single city unit.
• the Isthmus of Suez: the isthmus between North Africa and Southwest Asia, in Egypt where the Suez Canal is located
• the Isthmus of Kra, which joins the Malay Peninsula with mainland Asia
• the Isthmus of Avalon, Canada: separate the main island of Newfoundland from the Peninsula of Avalon (where the capital, St. John's, is located).
• the Isthmus of Chignecto: connects the mainland portion of Nova Scotia with North America
• the Isthmus of Tehuantepec: connects Yucatan and Central America with the rest of Mexico.
• the Isthmus of Perekop between Crimea and Ukraine proper.
• the Karelian Isthmus between Gulf of Finland and Lake Ladoga

Isthmuses are logical places to build canals. The Panama Canal, which connects the Atlantic and Pacific Oceans, drastically reduces the naval travel time between the east and west coasts of the Americas. The previously mentioned Suez Canal is another example — it allows ship transportation between Europe and Asia without the circumnavigation of Africa.

Isthmuses are the inverse of straits. That is, while isthmuses lie between two bodies of water and joins two larger land masses, straits lie between two land masses and connects two larger bodies of water.

See also: geography, Mainland