Bolivia's decision to take Chile to the International Court in The Hague on Wednesday is the latest step in one of Latin America's longest-running and bitterest diplomatic stand-offs.
The dispute dates from the late 19th Century when Chile went to war with the combined forces of Peru and Bolivia. The war was sparked by a row over taxation of the nitrate industry, a major source of income for Chileans working in what was then Bolivian territory.
Chile won the war and annexed 120,000 sq km of Bolivian land, an area roughly the size of Greece. Bolivia lost 400km of coastline as a result and has been landlocked ever since.
The two countries signed a peace treaty in 1904. Under its terms, Chile agreed to compensate Bolivia for its loss of land and give Bolivia access to Chilean ports. The Chileans also agreed to build a railway from their port of Arica to Bolivia's biggest city La Paz.
But the Bolivian President Evo Morales says the 1904 treaty was effectively imposed on his country down the barrel of a gun. He wants it scrapped or amended to give Bolivia sovereignty over the land it once owned. That is the essence of Bolivia's case in The Hague.
To rub salt into Bolivian wounds, the disputed land has proved extremely valuable to Chile. The nitrate plants have long closed but have been replaced by some of the world's biggest copper mines.
The Chileans say they are happy to talk to their northern neighbours over coastal access but under no circumstances will they cede sovereignty. Opinion polls consistently show that most Chileans support that stance.
Relations between the two countries have been poor for decades. Save for a brief spell in the 1970s, they have not enjoyed full diplomatic relations for about 60 years. There is no Bolivian ambassador in Santiago and no Chilean ambassador in La Paz.
There have been some attempts at rapprochement. The most important was the agreement of a 13-point plan, designed to resolve mutual differences. That plan remains on the table in theory but has been abandoned in practice as positions have hardened.
"We need to return to the 13-point plan. The process of discussing it was interrupted under the current Chilean government," says Gabriel Gaspar, an international relations analyst at Fundacion 21, a think tank in Santiago. "Both governments need to explain why that process has been halted."
Both countries would benefit from a settlement, particularly in terms of energy co-operation. Bolivia is rich in natural gas but refuses to sell it to energy-poor Chile. If the Chileans could buy fuel from Bolivia, it would go a long way to easing their energy problems and would give Bolivia an important source of income.
The countries have also argued about water rights. They dispute access to the river Silala, which rises in Bolivia but flows down the Andes into what is now Chile.
The Bolivians still have preferential access to Chile's northern ports, and export their goods through Arica and Antofagasta. But Mr Morales has complained that the Chileans have reneged on agreements to give Bolivia access to ports further south on Chile's long Pacific coastline.
In recent months, the dispute has descended into little more than a slanging match. In December, Bolivian Vice-President Alvaro Garcia described Chile as "the bad boy of the region" and as "unfriendly, provocative and aggressive".
Mr Morales came to Santiago in January for a meeting of Latin American leaders and dedicated his entire speech to berating Chile. Chilean President Sebastian Pinera responded in kind, telling his Bolivian counterpart to be more respectful of the truth.
In the same month, three Bolivian soldiers were arrested in Chile for straying into Chilean territory with a firearm. The incident sparked another sharp exchange of words.
Despite the animosity, there is little danger of armed conflict, particularly now the case has gone to The Hague. The Bolivian armed forces are no match for those of Chile, a much wealthier country.
Each year, on 23 March, Bolivians celebrate the Day of the Sea. It is a bizarre spectacle: thousands of people march through the streets of La Paz carrying model ships and pictures of the ocean. The Bolivian navy, which has no sea on which to sail, turns out in full uniform.
For now, that navy and the Bolivian people can only dream of coastal sovereignty. But they hope that with the help of The Hague, that dream can become reality.