The Asian Development Bank, the Australian and Nauru governments and the Green Climate Fund are contributing tens of millions of dollars to rebuild the Aiwo boat harbour.
Once complete the harbour will be the first fully functioning international port in Nauru.
The ADB said the Nauru Sustainable and Climate Resilient Connectivity Project would transform the largely inoperable boat harbour into an efficient, reliable, and climate-resilient port which will improve the quality of life on Nauru.
The ADB has given a grant of $US21.3 million, the Green Climate Fund $US26.91 million, Australia $US14.08 million, and Nauru $US17.3 million.
The chief executive of the Nauru Port Authority, Anton Jimwereiy, said Nauru has relied on the small boat harbour at Aiwo for about 110 years and it's time for an upgrade.
He said the upgrade would eliminate the cost of replacing the mooring system every five years, reduce other port costs, improve the efficiency and safety of employees, improve ship turnaround times and cut the cost of imports.