A cross-sea bridge, also known as a marine bridge, is a large-scale structure built over ocean waters such as bays, straits, or estuaries. These bridges often have a long span and can be several thousand meters or even dozens of kilometers in length.


Due to the harsh and complex natural conditions in the marine environment, building a cross-sea bridge requires advanced technology and engineering.


The classification of bridges can be based on their use, such as highway bridges, railway bridges, footbridges, and water bridges. Here are the top five sea bridges in the world:


1. Hong Kong-Zhuhai-Macao Bridge - With a total length of 55 kilometers, including 42 kilometers on the sea surface, this bridge is the longest cross-sea bridge in the world.


It has a service life of 120 years and can withstand typhoons of magnitude 16 and earthquakes of magnitude 8. The bridge connects the Hong Kong Port to Zhuhai and Macau and was opened to traffic in 2018.


2. Qingdao Bay Bridge - With a total length of 41.58 kilometers, this bridge is the second-longest sea bridge in the world. It opened to traffic in 2011 and has six lanes in both directions with a designed speed of 80 kilometers per hour.


3. Seto Bridge in Japan - Spanning the Seto Inland Sea between Honshu and Shikoku Islands, this bridge is made up of three cable bridges, two cable-stayed bridges, and one truss bridge with a total length of 37.3 kilometers.


The sea section is 13.1 km long. It opened to traffic in 1988 and is a road and railway bridge.


4. Chesapeake Bay Bridge - Spanning 37 kilometers between Maryland and Virginia, this bridge opened to traffic in 1964 and is considered one of the seven wonders of the modern world.


It offers views of the Atlantic Bay and the world's busiest shipping lane and is open to the public once a year for sightseeing by bicycle.


5. Hangzhou Bay Sea Bridge - With a total length of 35.673 kilometers, this bridge connects the cities of Jiaxing and Ningbo in China. It opened to traffic in 2008 and has six lanes in both directions with a designed speed of 100 kilometers per hour.


There are many other notable sea bridges around the world, each with its own unique features and challenges. Some other examples include:


The Oresund Bridge connects Denmark and Sweden and has a total length of 7.8 miles. It includes a road and railway bridge and a cable-stayed bridge.


The Golden Gate Bridge is located in San Francisco, California, USA. It is a suspension bridge spanning 1.7 miles and is one of the most iconic landmarks in the United States.


The Sea-to-Sky Highway in British Columbia, Canada, which includes a section of the Sea-to-Sky Gondola that passes over a fjord and offers spectacular views of the surrounding area.


The Rion-Antirion Bridge in Greece is a cable-stayed bridge spanning 2.25 miles and is considered one of the most significant engineering projects in the Mediterranean.


Overall, sea bridges are impressive feats of engineering and provide vital connections for communities, transportation, and commerce. They are also tourist destinations and offer great views of the surrounding areas.