Egypt has opened a major expansion of the Suez Canal, which deepens the main waterway and provides ships with a 35km (22 mile) channel parallel to it.
At the inauguration, Egyptian President Abdel Fattah al-Sisi welcomed foreign leaders aboard a historic yacht as helicopters and fighter jets flew by.
The expansion aims to increase the traffic handled by the canal.
Egypt’s government hopes the revenues will revive the economy – but analysts have questioned the projections.
They point out that the volume of world trade has not been growing at the pace needed to deliver the sums Egypt hopes to collect.
Egyptians commenting to the international press and on Twitter appear divided over the project, with many asking if the $8.2bn (£5.3bn) spent on the expansion could have been better deployed on improving infrastructure and public services.
The expansion will allow for two-way traffic along part of the route, as well as for larger vessels overall. The construction of the new lane began a year ago, on the orders of Mr Sisi.
At the inauguration ceremony in the town of Ismailia, the president appeared in military uniform and sunglasses aboard the El-Mahrousa – the yacht that was the first vessel to pass through the canal when it was built in 1869.
The former military leader, elected last year as a civilian, welcomed foreign guests including French President Francois Hollande and Russian Prime Minister Dmitry Medvedev.
Fighter jets and helicopters flew above the ceremony. On the streets of Cairo, banners described the expanded canal as Egypt’s “gift to the world”.
Pro-government media have hailed the expansion of the canal as a national triumph, and a turning point after years of instability.
However, many analysts doubt if the new venture will deliver the anticipated benefits.
Ahmed Kamaly, an economist with the American University in Cairo, told Reuters news agency that the Egyptian projections were “wishful thinking”.
“There was no viability study done, or known of,” he was quoted as saying. He added that the immediate benefits from the expansion were more likely to be political than economic, uniting people “around a national project”.
Takings from Suez could also be hit by an expansion of the Panama Canal, due to be completed next year, which will compete for traffic along the Asia-North America route.
Security was tightened for the inauguration ceremony amid fears of attack by militants allied to Islamic State.
The militants, based in the Sinai peninsula, have killed hundreds of people since the military overthrew the Islamist government of president Mohammed Morsi in 2013.
The original canal currently handles 7% of global sea-borne trade. The waterway connects the Mediterranean to the Red Sea, providing the shortest sea link between Asia and Europe.
Its nationalisation led to a brief war in 1956, pitting Egypt against the UK, France and Israel.