In this blog post, we’ll examine the necessity, economic benefits, and technical feasibility of a Korea-Japan undersea tunnel, as well as the reasons why its construction has not moved forward, and together consider the future direction of South Korea’s development.
Let’s Push for the Korea-Japan Undersea Tunnel
“Dreams Must Run. Toward the Korea-Japan Undersea Tunnel”
1592: The Imjin War.
1910: Korea was annexed by Japan through the Annexation Treaty of 1910.
1945: Korea regained its independence, but following the Korean War in 1950, the country became divided.
However, South Korea has since achieved remarkable economic growth and developed into an advanced nation standing shoulder-to-shoulder with Japan.
Due to their geographical proximity, South Korea and Japan have maintained an inseparable relationship since ancient times. The two nations have historically influenced one another significantly, and this relationship continues to this day. In particular, because South Korea experienced Japanese invasion and the Japanese colonial period, negative sentiments toward Japan persist throughout society.
Despite this situation, Japan has consistently proposed the construction of a Korea-Japan undersea tunnel since the 1970s. The vision is to connect Busan and Fukuoka and establish a land-based transportation network that extends through South Korea to China and the Asian mainland. Analysts have suggested that Japan—which, due to its island geography, relies on air and sea transport for logistics—could gain significant economic benefits if a land-based logistics network were secured.
In contrast, many in South Korea take a relatively cautious view of this proposal. In the short term, given the enormous costs involved in constructing an undersea tunnel, some question whether it is economically viable; in the long term, even if the route were to connect to the Asian mainland via North Korea, there is significant support for the view that the final destination must be Busan. This stems from concerns that if the final destination were to extend all the way to Japan, Busan might be reduced to nothing more than a stopover.
However, this perspective may be overlooking the bigger picture by focusing solely on immediate benefits. It is difficult to conclude definitively that the economic benefits South Korea would gain from the Korea-Japan Undersea Tunnel would be any less than those of Japan. In fact, from a long-term perspective, there is a possibility that South Korea could derive even greater value.
In this article, we will examine the economic necessity of the undersea tunnel, taking into account the characteristics of the South Korean economy—which is highly dependent on foreign markets—and evaluate its long-term effects through the principles of economic integration. Next, we will examine the technical factors that must be considered during the construction process, and finally, by analyzing the historical and economic factors that have prevented the construction of the Korea-Japan Undersea Tunnel to date, we will assess the necessity of its construction.
South Korea is a prime example of a nation that has achieved remarkable economic growth in just a few decades, despite its resource-poor environment. At the heart of this growth was a trade-centered growth strategy: importing raw materials from abroad, processing them using South Korea’s technological capabilities, and then re-exporting the finished products overseas.
However, due to the division of the Korean Peninsula, the country has been unable to fully leverage its geographical advantage as a peninsular nation, and logistics continue to rely largely on sea and air transport to this day. Within this structure, the South Korean economy is inevitably highly susceptible to the fluctuations of foreign trade.
In particular, Japan has long held a significant position as one of South Korea’s major trading partners. Excluding China and the United States, the scale of trade with Japan is substantial; and considering that most of this trade is conducted via sea and air, logistics connectivity with Japan is by no means an issue to be taken lightly.
If a land-based logistics network were established, what economic advantages would it offer compared to maritime transport? Maritime transport involves considerable time and cost in the process of loading and unloading cargo onto ships. Given that South Korea and Japan are geographically very close, the proportion of these loading and unloading costs relative to total transportation costs can be relatively high. Furthermore, if a rail logistics network were established via an undersea tunnel, it could significantly reduce transportation distance and time, which is expected to help improve logistics efficiency.
The benefits of economic integration extend beyond mere reductions in logistics costs. To illustrate this, let’s examine the principles of economic integration.
For example, suppose we are producing a single commodity of equal value. Let’s assume that South Korea relies heavily on labor input, while Japan relies heavily on capital input. If the movement of labor and capital between the two countries is restricted, South Korea would engage in labor-intensive production, while Japan would engage in capital-intensive production. On the other hand, if labor and capital can move freely, South Korean labor would migrate to Japan, while Japanese capital and technology would flow into South Korea, allowing for a more efficient allocation of production factors between the two countries.
As a result, even with the same amount of labor input, more capital can be utilized, and the likelihood of an increase in total output also rises. These effects of economic integration are cited as key factors driving productivity gains and economic expansion across nations.
Furthermore, a study published at the time analyzed the economic ripple effects of constructing a Korea-Japan undersea tunnel and found that the impact of the Japanese economy on the South Korean economy was approximately 20 times greater than the impact of the South Korean economy on Japan. This was presented as a case study demonstrating that various economic effects can arise when the economies of the two countries are closely linked.
Such examples are, to a certain extent, consistent with the logic behind economic integration in the European Union (EU). A prime example is the Øresund Bridge connecting Denmark and Sweden. By connecting to the European mainland via this bridge, Sweden established a foundation for the freer movement of capital and labor and was able to further strengthen its ties with the European economic bloc. Furthermore, the Channel Tunnel connecting the United Kingdom and France is also regarded as a prime example of how cross-border transportation infrastructure contributes to economic integration.
If South Korea and Japan were connected to form a de facto “one-day commuting zone,” as in the European examples, conducting economic activities across borders could become much easier than it is today. This is likely to have a positive impact on revitalizing the regional economies of both countries and fostering the development of new industries.
However, even if such economic advantages exist, these discussions are unlikely to be realistic if the project is not technically feasible. This is because the fact that undersea tunnels are already operating successfully in Europe does not mean that the same conditions would apply between South Korea and Japan. So, what technical factors should be considered in the construction of a Korea-Japan undersea tunnel?
First, since the Korea-Japan Undersea Tunnel is a massive project with a total length of approximately 200 km, a solid foundation capable of stably supporting the entire structure is essential. According to survey data from that time, the areas around the Korea Strait, the Tsushima Strait, and the Iki Strait were assessed to have relatively stable ground conditions, consisting mostly of hard sedimentary rock, igneous rock, and basalt.
The next factor to consider is ship traffic. The waters through which the undersea tunnel would pass are an international shipping lane used by numerous vessels traveling to and from the Port of Busan; therefore, the tunnel must not interfere with ship traffic. For this reason, the undersea tunnel option has been considered over a bridge. While building a bridge might reduce initial construction costs, it could make it difficult to maintain the smooth flow of large-scale ship traffic.
Furthermore, as this area is of significant military importance, the impact on the operations of submarines and warships must be minimized. Consequently, it has been proposed that the undersea tunnel be constructed by passing through the strata beneath the seabed. This approach has the advantage of reducing the impact on the marine ecosystem and helping to ensure relative stability even in the event of natural disasters.
Finally, the mode of transportation within the undersea tunnel is also a key consideration. Technically, various transportation systems can be established inside the tunnel; however, if a highway exclusively for passenger cars were constructed, large-scale ventilation facilities would be required to handle the exhaust gases generated within the long tunnel. This could impose a significant burden in terms of cost-effectiveness and maintenance. Consequently, it has been suggested that a rail-based transportation system, capable of simultaneously transporting large numbers of passengers and cargo, would be more suitable. Although the original text presents a maglev train as one alternative, this should be understood as just one of the proposals made at the time.
So far, we have examined the necessity of the Korea-Japan Undersea Tunnel, its resulting economic benefits, and the technical factors that must be considered. However, in South Korea, there are still many who view the Korea-Japan Undersea Tunnel with caution, and no full-scale push for the project has been made at the government level in either country.
From South Korea’s perspective, the reasons why the construction of the Korea-Japan Undersea Tunnel has not moved forward can be summarized into two main categories.
First are historical factors. Memories of Japanese colonial rule remain deeply ingrained in South Korean society, and conflicts between the two countries over historical and territorial issues persist. Given this reality, it is difficult for a large-scale joint project such as the Korea-Japan Undersea Tunnel to gain broad social consensus. Furthermore, the argument that Busan should serve as the central hub even if the Korean Peninsula’s rail network is eventually connected to Eurasia is also linked to these historical and political perceptions.
Second are concerns regarding economic viability. The construction of an undersea tunnel requires enormous costs; at the time, project costs of approximately 100 trillion won were discussed. Although Japan took a relatively proactive stance and conducted some preliminary surveys, concerns have also been raised that a project requiring such a massive injection of national funds could impose a very heavy economic burden if it fails to achieve the expected results.
So, what choice should South Korea, as it looks toward the future, make?
I believe that even amid the ongoing tensions between the two countries, the planning and review of the Korea-Japan Undersea Tunnel should continue. If South Korea and Japan remain fixated on past conflicts and miss the opportunity to expand the future logistics market, it will take longer for Northeast Asia to grow into a global logistics hub, and both countries may fail to capitalize on sufficient growth opportunities.
The relationship between South Korea and Japan can be compared to that of the United Kingdom and France. Although the two nations fought numerous wars over a long period, they chose to cooperate for the future and, as a result, strengthened their economic ties by pursuing various joint projects, including the Channel Tunnel. Considering these examples, from a long-term perspective, South Korea and Japan also need to explore various avenues of cooperation to ensure sustained economic development.
Of course, this does not mean we should immediately proceed with the project by securing the massive construction costs—exceeding 100 trillion won—in a short period. Rather, it means we should approach this as a long-term national project following thorough feasibility studies, technical verification, and social consensus.
If the Korea-Japan Undersea Tunnel were to be constructed, we could expect not only direct benefits from increased logistics volume but also various ripple effects—such as job creation, expanded corporate investment, and increased tourism along South Korea’s southern coast and in the Fukuoka region of Japan—alongside the economic integration effects discussed earlier.
In fact, the Channel Tunnel connecting the United Kingdom and France is widely recognized as having contributed to the development of northern France and the revitalization of the local economy. The author argues that if we consider not only the toll revenue from the undersea tunnel but also various indirect effects—such as balanced regional development, enhanced logistics competitiveness, and industrial revitalization—we can expect economic value exceeding the initial investment costs.
Furthermore, I do not believe there is cause for excessive concern that Busan will be reduced to a mere stopover even if railways are eventually connected through North Korea to the Asian continent and Europe. The study analyzed the growth potential of neighboring countries by assuming a scenario in which, following the construction of the Korea-Japan Undersea Tunnel, a railway would connect to Europe via North Korea.
The results indicated that South Korea would be the biggest beneficiary, followed by North Korea. This suggests that even if rail and road connections extend to Japan, South Korea’s growth potential would not necessarily be lower than Japan’s.
Rather, it is even more important to develop Busan into an international logistics hub that attracts people from around the world and to foster it as a focal point where global capital and logistics flows converge. From this perspective, the Korea-Japan Undersea Tunnel could serve as a starting point for South Korea’s growth into a logistics hub in Northeast Asia, and it would be advisable to continue consultations with Japan after comprehensively reviewing economic feasibility, technical viability, and diplomatic conditions over a sufficient period of time.
