Several parts combine into one character.

港 is a phonetic-semantic compound: 氵 (water) + 巷 (xiàng, "lane / alley" — providing the sound). The composite reads as "the lane where waters gather and meet" = harbor, port. From this maritime origin grew the modern extension to airports — though air-arrival was unimaginable to ancient Chinese, the conceptual leap from "ships gathering at water" to "planes gathering at land" worked cleanly through the metaphor of port-as-arrival-point.

Korean reading "hang." 港口 (hanggu, harbor / port — physical seaport), 空港 (gonghang, "sky-port" = airport), 港灣 (hangman, port / harbor), 入港 (iphang, entering port), 出港 (chulhang, leaving port), 釜山港 (Busan-hang, Busan Port), 仁川國際空港 (Incheon Gukje Gonghang, Incheon International Airport). Korean transportation and trade vocabulary leans on 항.

Mandarin gǎng, 3rd tone. 港 (gǎng), 港口 (gǎngkǒu, harbor), and most importantly 香港 (Xiānggǎng, "Fragrant Harbor" = Hong Kong — the city's name preserves an old Cantonese reference to the fragrant incense traded through its harbor in Ming and Qing times). Hong Kong's name in every CJK script reveals this poetic etymology. 上海港 (Shànghǎi gǎng, Port of Shanghai). For airports, modern Mandarin uses 机场 (jīchǎng, "machine-field"), not 空港.

Japanese on-reading コウ (kō) — 空港 (kūkō, airport — major Japanese vocabulary; 成田空港 Narita Airport), 港湾 (kōwan, harbor area). Kun-reading みなと (minato) — 港 (minato, harbor), 港町 (minatomachi, port town — evocative term for cities like Yokohama, Kobe, Nagasaki, Hakodate that defined Japan's connection to the outside world during the long isolation and after).

Memory aid: water (氵) + lane (巷) — where water-lanes converge = harbor.