Harbor Argostolíou is on the SW coasts of the namesake bay. The coasts of the harbor are quayed for about 1,425 m NW of the stone bridge at the head of the gulf, which separates it from lagoon Koútavos, and have depths of less than 2.5 m near them. The central wharf of the harbor, 210 m long and with depths of 5.4–6.2 m, is 0.5 miles NW of the above-mentioned bridge.

The Harbor Master`s Office and the Customs House are located in the S part. Immediately NW a small harbor has been built. At a distance of 0.8 miles NW of the root of the stone bridge a passenger quay has been built, with a T - shaped jetty that extends to 200 m NE. Its head is 65 m. long.

Harbor Argostolíou is a port of entry. The harbor can handle vessels with a total length of 150 m and a maximum draught of 6.2 m. The water density is 1025 g/cm3.