Top 10 countries with the largest submarine fleets in 2025

The global ranking of countries with the most submarines highlights ongoing military investments and strategic defence priorities. Nations continue to develop underwater capabilities for security and intelligence operations.

Submarines play a key role in naval strategy, serving as deterrents and intelligence-gathering platforms. Nuclear-powered ballistic missile submarines ensure second-strike capability, while attack submarines engage in anti-submarine warfare. Advances in sonar, radar, and electronic warfare enhance their effectiveness.

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Beyond military use, submarines contribute to ocean research and mapping. The development of unmanned submarines and autonomous underwater vehicles is expanding both defence and scientific applications in global maritime operations.

According to Global Firepower, here are the top 10 countries with the largest submarine fleets in 2025

United States

The United States remains the world leader in submarine strength, operating 70 submarines. The fleet consists of nuclear-powered vessels, including ballistic missile submarines, attack submarines, and guided missile submarines. The U.S. Navy prioritises technological advancements and global operational reach.

Russia

Russia maintains the second-largest submarine fleet with 63 vessels. The country continues to modernise its fleet, incorporating advanced nuclear and conventional-powered submarines. Russia’s underwater capabilities play a significant role in its defence strategy, with a focus on both deterrence and strategic operations.

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China

China ranks third with 61 submarines. The country continues to invest in expanding its naval capabilities, focusing on nuclear and diesel-electric submarines. China’s submarine fleet supports its maritime security interests in the Indo-Pacific region.

Iran

Iran ranks fourth with 25 submarines. The fleet includes a mix of midget submarines and conventional attack submarines. Iran’s focus remains on enhancing its regional defence capabilities, particularly in the Persian Gulf and surrounding waters.

Japan

Japan operates 24 submarines, securing the fifth position. The fleet consists mainly of advanced diesel-electric submarines designed for stealth and efficiency. Japan continues to upgrade its capabilities to ensure security in the Asia-Pacific region.

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South Korea

South Korea ranks sixth with 22 submarines. The country continues to enhance its naval strength with the development of new submarine models, focusing on defence against regional threats.

India

India ranks seventh with 18 submarines. The fleet includes nuclear-powered ballistic missile submarines and diesel-electric attack submarines. India’s naval strategy focuses on securing its maritime borders and expanding its underwater deterrence capabilities.

North Korea

North Korea operates 13 submarines, placing it eighth on the list. The fleet consists mostly of diesel-electric submarines, with an emphasis on regional deterrence and coastal defence.

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Turkiye

Turkiye also operates 13 submarines, ranking ninth. The fleet is primarily composed of diesel-electric attack submarines. Turkiye continues to modernise its naval forces to maintain security in the Mediterranean and surrounding waters.

Greece

Greece ranks tenth with 10 submarines. The fleet consists of diesel-electric submarines designed for regional defence and operational readiness in the Mediterranean.