The Singapore Strait connects the Straits of Malacca with the South China Sea.
It is one of the busiest shipping lanes in the world, with ships supplying energy heading to China and the rest of East Asia and Asian-manufactured goods heading west.
At the mouth of that bottleneck lies a tiny island about the size of a football field with a lighthouse on it.
Singapore owns the island, but Malaysia also claims it, and Malaysia is taking Singapore to the International Court of Justice over that ownership.
Australian National University law professor Donald Rothwell says, despite the island's size, its strategic location and maritime rights like fishing and energy exploration make it significant.
"Singapore in particular, because it's very constrained by the geographic proximity of Malaysia and, to a lesser extent, Indonesia, is not entitled to assert the same maritime claims as many of the neighboring states, just because it's geographically compromised. Even though these features are very small, they are well worth contesting because of the potential maritime entitlements they generate."
The island lies about 40 kilometres east of Singapore's main island and 19 kilometres south of Malaysia.
Singaporeans refer to it as Pedra Branca, meaning "white rock" in Portuguese, a reference to the bird droppings that cover the rocks.
The Malaysians call it Pulau Batu Puteh, which, in Malay, also means "white rock island."
The dispute goes back to Singapore's independence after it was expelled from the Malaysian Federation in 1965, two years after the union of British colonies was formed.
The director of the Asia Institute at the University of Tasmania, James Chin, says, in 2008, when the court ruled in Singapore's favour, the Malaysian public was furious.
Professor Chin says Malaysia had not handled the case professionally.
"There were major, major criticisms across the board in Malaysia about the way that the whole thing was conducted by the Malaysia delegation. So, for example, they took a photo that later turned out to be photoshopped as evidence to the ICJ."
Malaysia is requesting the court review its 2008 decision on the basis of new documents recently discovered in British archives.
The new evidence was uncovered last year and includes colonial telegrams and navy logs.
Malaysia and Singapore have had a rocky relationship over the years, particularly during the 1980s and '90s under previous leaders.
But Professor Chin says the relationship had been improving.
"The way I describe the Singapore-Malaysia relationship is, basically, they're a divorced couple. You know, they're still linked for historical reasons because they were married at one time, but there are lots of underlying issues that haven't been resolved."
Malaysian prime minister Najib Abdul Razak is facing a general election in the next 18 months.
Some political analysts suggest he is revisiting the island dispute because it is popular with the electorate.
Mr Chin says he does not believe that is the case, but he says Mr Najib will use the dispute on the campaign trail.
"I think it's just lucky timing on Najib's side. Of course, he can use this as one of his election-campaign issues, that he's trying very hard to win the islands back for Malaysia."
In Sydney, the director of the Lowy Institute's International Security Program, Euan Graham, says the dispute risks souring the relationship between the two neighbours again.
Both are part of ASEAN, the regional union recently under strain over conflicting positions between various members on the South China Sea.
"It is inevitably a distraction at a time when countries within ASEAN are feeling more fractured than ever and when, really, they could do without this extra thorn in the side of South-East Asian cooperation."
There is also the broader South China Sea conflict.
China has recently been improving military and economic ties with Malaysia, while Singapore remains a staunch ally of the United States.
Dr Graham says, while he is not sure if China is involved in Malaysia's decision to revisit the case, it will benefit regardless.
"It suits China for Malaysia and Singapore to be arguing with each other, rather than reaching common purpose, which ... you know, the larger strategic interest is in South-East Asian countries cooperating more with each other to resist bullying from China."
