Entering its eighth decade since independence, Indonesia still faces the same challenges that stem from the vast geography of seas, waterways and coastal areas that make up around 71 percent of its territory.

While administrative disputes over regional islands continue to surface, there is also no stopping the unassailable fact that Java, the country’s most populous island and home to its political and business hub Jakarta, is sinking.

Perhaps former president Joko "Jokowi" Widodo was trying to solve this problem by abandoning Jakarta altogether and relocating to the new Nusantara Capital City (IKN) development in East Kalimantan.

President Prabowo Subianto is now in power, and he seems less enthusiastic about moving the nation’s capital to Nusantara.

Rather than allocating more funds to resume his predecessor’s legacy megaproject, he has revived the old idea of building a “Giant Sea Wall" to protect Java's northern coast, including Jakarta, from chronic flooding and land subsidence. The seawall has been included on the new list of national strategic projects in the 2025-2029 National Medium-Term Development Plan.

Both these plans are costly and difficult. And for Prabowo to drag on the IKN project in exchange for pivoting to the seawall project does not prove he has better judgment or sense of priority compared to his predecessor.

The northern coast of Java is indeed sinking, and at an alarming rate. A study shows that Jakarta in the island’s northwest is sinking between 1 and 11 centimeters a year, while coastal cities in Central Java like Pekalongan, Semarang and Demak are subsiding as much as 20 centimeters annually, driven by excessive groundwater extraction and in some areas, oil and gas exploitation.

More than 150 million people live on Java, many along the island’s northern coast. From this perspective, building a coastal barrier for the island could become an emergency measure akin to projects in small Pacific island states facing multiple coastal hazards, albeit primarily due to climate change.

But no clear plans have been made so far aside from bringing up old embankment projects in Jakarta for somehow connecting the new seawall to the ongoing Semarang-Demak toll road project in Central Java. Despite the unclear design for the seawall, which will span roughly 500 kilometers from Banten to East Java, the project has an estimated cost of up to US$80 billion over 20 years.

There are also proposals to incorporate a reclamation project for building a livable seawall that has residential and commercial zones, essential turning the whole structure into a kind of floating city.

Asked how the seawall project would be financed, the President said the money should come from both the central government and the Jakarta administration, only raising more questions about how Java’s other northern coastal provinces might participate.

Environmentalists have warned about the seawall weak blue print, as well as its potential environmental repercussions and state losses if the project fails. These concerns arise from the failures of smaller sea dikes in Jakarta to protect Muara Karang and Muara Angke from tidal flooding and land subsidence.

There are also many examples of the government’s lack of attention to the environmental impacts of megaprojects and other strategic infrastructure that have led to disaster. Mining operations are among those recently reported, and even the IKN project has caused social and environmental problems that continue to flare up regardless of the Prabowo administration’s shift in priority.

Simply put, we don’t have enough money or possess the knowledge or experience to build the Java seawall. Unless Prabowo and his administration put more time and thought in its planning and get experts and investors on board, the seawall project will simply reinforce the perception that a president can act on a whim without considering the costs and risks.

If so, we could end up with another unfinished massive construction by the end of the current presidential term, only this time at sea.