The seven islands: what we know about Iran's maritime line controlling Hormuz

As Iran continues to keep the Strait of Hormuz closed, the question is no longer limited to the impact of the closure on global energy markets and the economy.

It has shifted to uncovering the mechanisms Iran uses to control what is currently the world's most sensitive shipping route.

This does not refer to Iran's military capabilities but rather to a complex network of strategic islands whose function Iran has reshaped, turning them into "fixed aircraft carriers" through which it controls shipping traffic in the Strait of Hormuz.

Geographically, the Strait of Hormuz, located south of Hormozgan province, forms a natural boundary between Iran and Oman.

It is a narrow passage constrained by navigational challenges. Strong water currents and varying depths force giant tankers to follow specific and extremely narrow routes, increasing Tehran's ability to control and monitor them.

The area derives its strategic importance from being the world's second-busiest strait, with about 17 million barrels of crude oil passing through it every day.

This represents 40% of oil transported by sea and about 25% of total global supplies, in a region that alone holds 68% of the world's proven oil and gas reserves.

Characteristics of the Strait of Hormuz

The Strait of Hormuz is estimated to be 167 kilometres long, while its width varies depending on the area.

It reaches about 95 kilometres at its widest point and narrows to about 33 kilometres at its narrowest.

However, official shipping lanes are much narrower. Each lane designated for vessel traffic is no more than 3 kilometres wide, with a buffer zone separating the inbound and outbound lanes.

The depth of the Strait of Hormuz also varies, reaching more than 60 metres in some areas, while ranging between 30 and 40 metres in shallow areas.

Although this depth is suitable for giant oil tankers and heavy vessels, it forces large ships to follow specific and limited routes, increasing the area's security importance.

The narrowest point of the strait is 21 nautical miles wide, located between Iran's Larak Island and Oman's Greater Quoin Island.

Until 1979, shipping traffic followed the shortest route between the Quoin and Musandam islands.

That year, Oman announced that vessels should pass through an area outside the range of Quoin Island in order to reduce security risks to routes near its islands and territory.

For about 60 years, the shipping route in the Strait of Hormuz passed through Iranian territorial waters.

But Tehran rejected this after it was subjected to war and closed the strait, announcing the opening of a northern route for vessels after they obtained permission from the Iranian navy.

Iran has also held negotiations in recent weeks with Oman to establish a new shipping route.

An agreement was reached, although it was not announced. However, Iranian authorities continue to refuse to reopen the Strait of Hormuz without a response from Washington to its conditions for ending the war permanently, lifting the blockade and sanctions, releasing its frozen assets and other demands.

An island shield to retain Hormuz

Iran's ability to control the Strait of Hormuz is not limited to its coastal capabilities stretching for about 160 kilometres.

A group of Iranian islands also plays a vital role in strengthening this control within these waters.

These islands have given Iran a unique geopolitical position at the entrance to the Gulf, allowing it to control the strait and traffic passing through it.

Seven islands form Iran's curved defensive line in the area for controlling shipping traffic: Hormuz, Larak, Qeshm, Hengam, Greater Tunb, Lesser Tunb and Abu Musa.

The last three islands are disputed between Iran and the United Arab Emirates but are currently under Iranian control.

Four of these islands are located at the entrance to the strait — Hormuz, Qeshm, Larak and Hengam — while the other three disputed islands lie west of this curved line.

The short distances between these islands and the depth of the waters in this area force warships and oil tankers to pass close to them when entering the Strait of Hormuz.

This currently exposes these vessels to threats from fast boats, mines or drones stationed on the islands.

These islands are so important to Iran that former Iranian navigation official Ali Ezzati described them in a statement as "fixed aircraft carriers that cannot be sunk".

The seven islands

1 — Hormuz Island

The island is about 8 kilometres wide and is located 20 kilometres south of Bandar Abbas port.

Over the past centuries, Hormuz has been regarded as the key to entering the Gulf. The naming of the strait after it is evidence of this status.

The island is oval-shaped, covering about 42 square kilometres along the strait, and is a tourist destination in southern Iran.

Hormuz City is located in the north and is the island's only population centre. Its population stood at 5,891 according to the 2016 census.

It was under Portuguese occupation for more than a century before Iran regained control of it in 1622 under Shah Abbas.

The Iranian Achaemenid Empire used the island as a naval base more than 2,500 years ago.

Throughout history, it served as a commercial meeting point for traders from India, China and other eastern markets.

The Portuguese viewed it as an impregnable fortress overlooking the meeting point between the Gulf waters and the Indian Ocean.

In the modern era, which has seen the passage of giant oil tankers, Hormuz Island has retained its strategic position despite its relative distance from the deep-water shipping channel.

2 — Larak Island

Larak is located 40 kilometres south of Bandar Abbas, the centre of Hormozgan province, 20 kilometres west of Hormuz Island and 12 kilometres east of Qeshm Island.

Larak is unique in being the Iranian island directly adjacent to the deep-water channel in the Strait of Hormuz that is suitable for the passage of giant oil tankers.

Since Iran announced the closure of the Strait of Hormuz following the US-Israeli war on 28 February, Larak has been closely linked to developments involving the shipping route.

The Islamic Revolutionary Guard Corps launched an alternative route for shipping through Iranian territorial waters, bypassing the historic route that passed through Omani waters.

The new Iranian route passes south of Larak Island, overlooking the vital energy corridor, making its location the main pillar of Tehran's military system aimed at retaining control over the Strait of Hormuz.

The island lies at the easternmost point of the Gulf and is administratively part of Iran's Hormozgan province.

It is oval-shaped and extends 10.5 kilometres from northeast to southwest.

3 — Qeshm Island

Qeshm is the largest island in the Gulf, with an area twice that of Bahrain, which is the second-largest island in the region.

Qeshm is located 20 kilometres south of Bandar Abbas, 40 kilometres east of Bandar Lengeh and 31 kilometres east of Greater Tunb.

It is 140 kilometres long.

Qeshm is characterised by its sandy terrain, with hills spread across its central areas.

The highest point is Mount Buko, which rises 405 metres above sea level.

The island covers 1,644 square kilometres and is rich in natural resources, including oil, gas, lead, sulphur and salts.

The island had a population of 148,993 in the 2016 census, with 66,801 living in urban areas and 82,160 in villages and towns.

Over the past decade, Qeshm has become a prominent tourist destination because of its environment and natural and historical sites.

Parts of it have been part of the Global Geoparks Network under the auspices of UNESCO since 2006, as the first geopark in the Middle East.

4 — Hengam Island

Hengam is located just 3 kilometres south of Qeshm Island.

It is about 50 kilometres from Oman's Ghanam Island and shares with Larak Island direct oversight of the deep edge of the shipping routes in the Strait of Hormuz.

The island contains scattered population centres across an area of about 50 square kilometres south of Qeshm.

It contains deposits of salt, soil and lead.

It is 10 kilometres long and between 3 and 6 kilometres wide.

During the Qajar monarchy, Britain established facilities and military bases on the island.

Hengam's coastline is suitable for deploying fleets and naval vessels because of the deep waters surrounding its shores, making it suitable as a berth for warships and submarines.

Its location in the middle of the Gulf waters, adjacent to the Strait of Hormuz and Qeshm, has given it major strategic and military importance.

This has made it historically vulnerable to attempts at control by successive foreign powers.

It was occupied by the Portuguese during the Safavid era and later by the British during the Qajar period.

5 — Greater Tunb

Greater Tunb is one of three islands disputed between Iran and the UAE.

It lies 31 kilometres southwest of Qeshm Island and faces the Strait of Hormuz to the west.

The island is one of the main pillars of Tehran's defence and military doctrine for protecting and managing the strait.

The island is 12 kilometres from Lesser Tunb, 50 kilometres from Abu Musa and about 82 kilometres from Al Hamra Island in Ras Al Khaimah.

It lies north of the Gulf's median line and is roughly circular, covering about 12 square kilometres.

It is predominantly dry and sandy, with little vegetation, while hills in the north reach a maximum height of 53 metres.

6 — Lesser Tunb

Lesser Tunb is the other disputed island between Tehran and Abu Dhabi.

It lies on the northern side of the Gulf's median line, 12 kilometres from Greater Tunb, 50 kilometres from Bandar Lengeh and 92 kilometres from the coast of Ras Al Khaimah in the UAE.

The island covers only about 2 square kilometres, which explains the name "Lesser".

It is roughly triangular in shape, with a width ranging between 1,100 and 1,500 metres.

A dark rocky hill rises 35 metres above sea level in its northwestern part.

Its shores are steep, amid a hot and humid climate, and it has no fresh water.

Unlike Greater Tunb, it is uninhabited and is predominantly used for military and security purposes related to protection and surveillance.

Its spread of rocks and salt domes gives it rugged terrain.

7 — Abu Musa

Abu Musa is the third island disputed between Iran and the UAE.

It forms the westernmost point of Iran's maritime defensive arc and is the final link in the Iranian defence system stationed at the Gulf's gateway.

It is 67 kilometres from Bandar Lengeh and 62 kilometres from Sharjah port in the UAE.

The island has an airport and a seaport, with regular flights operating between it and Bandar Abbas.

There are also passenger sea transport services using boats and vessels departing from Bandar Lengeh two to three times a week.

Its area is larger than that of both Greater Tunb and Lesser Tunb.

It has an irregular shape, while its central and southern areas are flat and sandy.

Its oil resources are limited to the Mubarak field, located offshore to the east of the island.

Its oil is classified as among the highest-quality crude extracted in the Gulf basin.

Revolutionary Guard Navy responsible for security

According to Iran's naval military divisions and formations, the first and fifth naval regions of the Islamic Revolutionary Guard Corps Navy are responsible for securing this curved defensive line and its surrounding area in the Strait of Hormuz.

The First Naval Region, known as "Sahib al-Zaman", is one of the five naval regions of the Revolutionary Guard.

It operates under the supervision of the naval force and the "Khatam al-Anbiya 2" naval headquarters.

The command headquarters of this region is located in Bandar Abbas.

It is the formation closest to the Strait of Hormuz and is responsible for conducting defensive and offensive operations in the area of the passage.

Rear Adm. Abbas Gholamshahi commands it.

On 4 November 2012, the Revolutionary Guard Navy established its Fifth Naval Region, named "Imam Mohammad Baqer", in Bandar Lengeh, overlooking the Gulf waters west of the Strait of Hormuz.

It assigned the region responsibility for controlling the area extending from the end of Qeshm Island, through an area of four islands that became known militarily as the "Naz'at" islands, to the west of Kish Island.

Under this military division, protection and security of the Strait of Hormuz itself was assigned to the First Naval Region as a direct naval mission.

The Fifth Naval Region, meanwhile, was independently tasked with protecting and securing the "Naz'at" island system in the western extension of the Strait of Hormuz.

The four defensive Naz'at islands are Greater Tunb, Lesser Tunb, Abu Musa and Siri Island.

Tehran relies on a diverse and hybrid arsenal to close or obstruct shipping through this strategic passage.

It combines coastal and mobile weapons along the coast and islands, ranging from underground missile cities and naval and coastal anti-ship missile launchers to fast boats, attack drones and naval mines capable of blocking the route of giant tankers.

Iran also relies on military capabilities beyond its coasts and islands, in both its missile and drone capacities, to tighten its control over the Strait of Hormuz.

Iranian army spokesman Mohammad Akram Nia previously said that "Iran can establish control over the Strait of Hormuz from any point on its territory".

Article translated from Arabic by Afrah Almatwari. To read the original, click here.