It has been suggested that the outer harbour was constructed between the years 312/311 and 294 BCE, during a period when Cyprus became an arena of conflict between two powerful successors of Alexander the Great, Ptolemy I Soter and Antigonus Monophthalmus, who both claimed rule of the eastern Mediterranean. As naval battles played a key role in these wars, safe mooring of the fleets acquired a geostrategic significance. These conditions have led to the hypothesis that the harbour of Amathus was constructed as a naval base. Its narrow entrance, around 20m wide, makes this interpretation plausible. Nonetheless, a combined commercial use of the harbour cannot be dismissed (click + to view a 360° model of the harbour).

There are good indications that the Amathus harbour was a short-lived project, or even that it was abandoned before it was ever finished. Even though the reasons for its abandonment remain unclear, silting must have been a decisive factor. If silting was caused by natural phenomena, the lack of preventive measures raises questions, considering the large scale of the project. Another interpretation, still difficult to prove, argues that silting was intentional: if the harbour was constructed by Demetrius Poliorcetes, son of Antigonus Monophthalmus, then Ptolemy I might have closed it and filled it in, following his conquest of the island in 294 BCE. Moreover, it is also possible that the fate of this major endeavour was sealed by an unfortunate combination of natural causes and political decisions.

The trapezoid basin of the harbour, with its narrow side facing the sea, covers an area of three hectares, or 30,000 square meters, and is demarcated by three moles: the east and the west moles extend perpendicular to the coast and the south mole runs parallel to it.  The inner side of the moles had quays constructed with tiers of header blocks, while concentrations of boulders formed a breakwater on the outer side of the south mole. The entrance is situated on the southeast corner of the harbour, protected by the west-southwest winds. At this spot, the ends of the south and east moles form corners (view by clicking on +) towards the east and the south respectively.

Ιt is estimated that around 5000 blocks were used for the construction of the harbour. They were probably extracted from quarries of the area, from the coast west of the harbour and from the neighbouring hill Vikles, at the north-east. Their length ranged from 1 to 3m and their weight from 1 to 4 tons. Their different sizes probably served the construction needs or was determined by the actual shape of the natural rock in the adjacent quarries.

Two to eight layers of blocks were excavated at different parts of the moles. Alternating layers of headers and stretches are preserved at the end of the south mole, which increased the durability of the construction.

Some of the blocks retained bosses at their narrow sides, that is protrusions to tie the ropes of lifting machines used for their transportation and placement. Six different types of bosses have been documented at the harbour of Amathus.

The foundations of the harbour moles have not as yet been documented completely. It is possible that the construction lay on a bed of pebbles and stones positioned directly on the seabed. This faulty construction method could have led to the partial submergence of the construction under its own weight.