For loading and unloading of boats or ships round the clock, the access channel and its expanded part-a port are excavated on the lagoon and ocean reef flats in the tropic Pacific oceanic islands. Without moles, the access channel port traps sediment and further transports it to the ocean or lagoon, resulting in coastal erosion. The wide uneven reef flat with a large catchment area tends to cause the formation of tide currents in the channel port, while strong waves on the narrow even reef flat can give rise to rip currents. An access channel port with a mole on one side or two moles on both sides results in less erosion. A model is recommended as an artificial harbor on the ocean coast, which is an excavated port surrounded by a mole, connected with the ocean by an access channel and with the shore by a bridge shaped pier. For loading and unloading of boats or ships round the clock, the access channel and its expanded part-a port are excavated on the lagoon and ocean reef flats in the tropic Pacific ocean islands. Without moles, the access channel port traps sediment and further transports it to the ocean or lagoon, resulting in coastal erosion. the wide uneven reef flat with a large catchment area tends to cause the formation of tide currents in the channel port, while strong waves on the narrow even reef flat can give rise to rip currents . An access channel port with a mole on one side or two moles on both sides results in less erosion. A model is recommended as an artificial harbor on the ocean coast, which is an excavated port surrounded by a mole, connected with the ocean by an access channel and with the shore by a bridge shaped pier.