Which are the Top 10 Longest Cross-Sea Bridges in the World? Cross-sea bridges represent some of humanity’s most ambitious engineering achievements, connecting cities, nations, and continents while overcoming vast stretches of open water. These structures blend innovation with practicality, reshaping transportation networks and economies. Below, we explore the world’s 10 longest bridges spanning seas, bays, and lakes, highlighting their design, impact, and technological brilliance.

Rank	Bridge Name	Length	Location	Completion Year	Key Features
1	Hong Kong–Zhuhai–Macau Bridge	55 km	Pearl River Delta, China	2018	Bridge-tunnel hybrid, 120-year lifespan, typhoon-resistant design
2	Jiaozhou Bay Bridge	42.5 km	Qingdao, China	2011	Over 5,000 concrete pillars, six-lane highway
3	Lake Pontchartrain Causeway	38.44 km	Louisiana, USA	1956/1969	Twin bridges, Guinness World Record holder for longest continuous over-water span
4	Donghai Bridge	32.5 km	Shanghai, China	2005	S-shaped alignment, supports Yangshan Deep-Water Port
5	King Fahd Causeway	25 km	Saudi Arabia–Bahrain	1986	Five bridges, artificial islands, four-lane highway
6	Vasco da Gama Bridge	17.185 km	Lisbon, Portugal	1998	Europe’s longest, withstands 250 km/h winds
7	San Francisco–Oakland Bay Bridge	13 km	California, USA	1936	Double-deck design, post-earthquake retrofit with self-anchored suspension
8	Seven Mile Bridge	10.89 km	Florida Keys, USA	1982	Part of Overseas Highway, 440 precast concrete spans
9	Øresund Bridge	7.8 km*	Denmark–Sweden	2000	Combined road/rail bridge, includes undersea tunnel (total length 16 km)
10	Mackinac Bridge	8 km	Michigan, USA	1957	Suspension design, 42,000 miles of cables, nicknamed “Mighty Mac”

1. Hong Kong–Zhuhai–Macau Bridge (55 km)

Location: Pearl River Delta, China
Completion: 2018

This 55-kilometer bridge-tunnel system links Hong Kong, Macau, and Zhuhai, integrating three cable-stayed bridges, an undersea tunnel, and four artificial islands. Designed to withstand typhoons and earthquakes, it reduced travel time between the cities from 4 hours to 45 minutes. The $18.77 billion project features a 6.7-kilometer submerged tunnel to avoid disrupting maritime traffic. Its 120-year lifespan and hybrid structure make it a benchmark for mega-scale marine engineering.

2. Jiaozhou Bay Bridge (42.5 km)

Location: Qingdao, China
Completion: 2011

Spanning Jiaozhou Bay, this 42.5-kilometer bridge cuts travel time between Qingdao and Huangdao by 30 minutes. Its six-lane highway sits atop over 5,000 concrete pillars, with a cable-stayed section allowing ships to pass. Built in just four years, it held the title of the world’s longest cross-sea bridge until the Hong Kong-Zhuhai-Macau Bridge surpassed it.

3. Lake Pontchartrain Causeway (38.44 km)

Location: Louisiana, USA
Completion: 1956 (southbound), 1969 (northbound)

This twin bridge system stretches 38.44 kilometers across Lake Pontchartrain, earning the Guinness World Record for the longest continuous bridge over water. Supported by 9,500 concrete pilings, its low-profile design withstands hurricanes and tidal surges. The causeway remains vital for commuters between New Orleans and Mandeville, carrying over 40,000 vehicles daily.

4. Donghai Bridge (32.5 km)

Location: Shanghai, China
Completion: 2005

Connecting mainland Shanghai to the Yangshan Deep-Water Port, this 32.5-kilometer bridge combines viaducts and cable-stayed segments. A 420-meter central span accommodates large vessels, while its S-shaped alignment mitigates tidal forces. The bridge supports China’s busiest port, handling 30% of the nation’s container traffic.

5. King Fahd Causeway (25 km)

Location: Saudi Arabia–Bahrain
Completion: 1986

This 25-kilometer causeway features five bridges and artificial islands, bridging the Gulf of Bahrain. Its four-lane highway strengthened economic ties between Saudi Arabia and Bahrain, facilitating trade and tourism. Construction required 350,000 cubic meters of concrete and 47,000 metric tons of steel.

6. Vasco da Gama Bridge (17.185 km)

Location: Lisbon, Portugal
Completion: 1998

Europe’s longest bridge spans the Tagus River, alleviating traffic in Lisbon. Its cable-stayed design includes a 420-meter main span and a clearance of 45 meters for ships. Built to last 120 years, it withstands winds up to 250 km/h and seismic activity.

7. San Francisco–Oakland Bay Bridge (13 km)

Location: California, USA
Completion: 1936

This iconic double-deck bridge combines suspension spans, a cantilever section, and a tunnel through Yerba Buena Island. After a segment collapsed in the 1989 Loma Prieta earthquake, a $6.5 billion retrofit replaced the eastern span with a self-anchored suspension bridge.

8. Seven Mile Bridge (10.89 km)

Location: Florida Keys, USA
Completion: 1982

Part of the Overseas Highway, this bridge arcs over the Atlantic Ocean and Gulf of Mexico, offering panoramic views. Its predecessor, a 1912 railroad bridge, was repurposed for vehicles after a 1935 hurricane. The modern version uses 440 precast concrete spans.

9. Øresund Bridge (7.8 km bridge section)

Location: Denmark–Sweden
Completion: 2000

Though its total link (including a tunnel) spans 16 km, the bridge section stretches 7.8 kilometers across the Øresund Strait. This combined road-and-rail structure connects Copenhagen and Malmö, fostering a binational economic region.

10. Mackinac Bridge (8 km)

Location: Michigan, USA
Completion: 1957

Nicknamed “Mighty Mac,” this suspension bridge links Michigan’s Upper and Lower Peninsulas over the Straits of Mackinac. Its main span stretches 1,158 meters, supported by 42,000 miles of cable.

Honorable Mention: Danyang–Kunshan Grand Bridge
While the 164.8-kilometer Danyang–Kunshan viaduct holds the Guinness record for the world’s longest bridge, only a portion spans Yangcheng Lake. Its primary role as a railway viaduct over mixed terrain excludes it from dedicated cross-sea lists.

Conclusion

These cross-sea bridges exemplify human ingenuity, transforming geographic barriers into conduits for progress. From China’s mega-projects to America’s historic causeways, each structure reflects unique engineering solutions tailored to environmental and economic demands. As maritime trade and urbanization grow, such bridges will remain pivotal in shaping global connectivity.

---