Isthmus

In ichthyology, the isthmus is the narrow area between the gill openings on the underside of a fish's head.

The sandy isthmus connecting North and South Bruny Island

The Isthmus of Panama

An isthmus (/ˈɪsməs/) is a narrow strip of land connecting two larger land areas. Of note, the Isthmus of Panama connects the continents of North and South America (the Americas), and the Isthmus of Suez in Egypt connects Africa and Asia (or Eurasia). The English plural of isthmus is either isthmuses or isthmi.

Canals are often built on isthmuses where they may be particularly advantageous to create a shortcut for marine transportation. The Panama Canal bisects the Isthmus of Panama, thereby connecting the North Atlantic and Pacific Oceans; the Suez Canal adjoins the North Atlantic and Indian Oceans, cutting across the Isthmus of Suez to connect the Mediterranean Sea and the Gulf of Suez/Red Sea.

List of Isthmuses

In Southeast Asia

The Isthmus of Kra is the narrow land bridge which connects the Malay Peninsula with the mainland of Asia. The east part of the landbridge belongs to Thailand, the west part belongs to the Tanintharyi division of Burma. To the west of the Isthmus is the Andaman Sea, to the east is the Gulf of Thailand.

In North America

West Coast

• Catalina Isthmus, which connects the larger eastern portion of Santa Catalina Island, California with its smaller western portion.
• Isthmus of Olympia, Washington, North America. Located at the base of Puget Sound, this isthmus connects West Olympia to East Olympia, and creates a separation between Capitol Lake and Budd Inlet, the southernmost point of Puget Sound.

East Coast

• Isthmus of Avalon, which connects the populous Avalon Peninsula to the rest of Newfoundland.
• Isthmus of Chignecto, which connects the Nova Scotia peninsula to the rest of Canada.
• Isthmus of Nahant connecting Nahant, Massachusetts to Massachusetts.
• Isthmus of Saint Pierre and Miquelon, which connects the island of Miquelon and Langlade Island
• Isthmus of Summerside, connecting the Western section of Prince Edward Island, Canada with the remainder of the island.

Midwest

• Madison Isthmus, between Lake Mendota and Lake Monona in Madison, Wisconsin.

Middle America

• Middle America - the isthmian tract of land that comprises the southern mainland of North America, connecting it with South America, i.e., the American landmass between the southern Rocky Mountains in the southern United States and the northern tip of the Andes in Colombia.
  • Central America: the tapering tract of land comprising the southernmost portion of mainland North America (and Middle America), extending from the Isthmus of Tehuantepec to the Isthmus of Panama, which connects with South America on the southeast.

Mexico

• Isthmus of Tehuantepec - in southeastern Mexico, the western frontier of Central America which represents the shortest distance overland between the Gulf of Mexico and the North Pacific Ocean

Panama

• Isthmus of Panama - connects North and South America. The Panama Canal goes through this isthmus.

In Oceania

In Australia

• Isthmus near Port Arthur, Tasmania, Australia
• Neck in Bruny Island, Tasmania - connects North and South Bruny.

New Zealand

• Auckland isthmus, which connects the Northland Peninsula to the rest of New Zealand's North Island. The narrowest section between the Manukau Harbour and the Tamaki River (a bay, despite the name) is barely 2km wide, even though Northland extends over 300km further.

Hawaii

Maui Hawaii

In Europe

North Coast

• Karelian Isthmus between Gulf of Finland and Lake Ladoga, which connects Russia to Finland.

Mediterranean Sea

• Isthmus of Bolbs, which joins Gibraltar to mainland Spain.
• Isthmus of Corinth, which connects the Peloponnese peninsula to the rest of Greece.
• Isthmus of Potidea, connecting the Kassandra peninsula with the mainland of Greece.

Black Sea

• Isthmus of Perekop between Crimea and Ukraine proper.

Red Sea

• Isthmus of Suez - the isthmus between North Africa and Sinai Peninsula, in Egypt where the Suez Canal is located.

British Isles

• La Coupée isthmus in Sark.
• Forth-Clyde isthmus in Scotland.
• Mavis Grind isthmus in Shetland, UK.
• Tyne-Solway Isthmus in England, along the Stanegate in Roman times main forts at Corbridge and Carlisle.

Atlantic Ocean

• Isthmus of Westfjords peninsula, which connects to the mainland of Iceland.

In South America

• Isthmus of Médanos - links Venezuela to Médanos.
• Ofqui Isthmus, Aisén Region, Chile.

See also

• Geography
• Mainland
• Tombolo
• Peninsula
• Land bridge