Ngarai Sihanok / Sianok is a beautiful valley in Bukittinggi, West Sumatera of Indonesia. The valley was formed because of The Great Sumatran Fault System movement. The valley is surrounded by giant steep cliffs made by mother nature, with height of 100 metres, length of 15 km, and width of 200 metres. It is surrounded by green tropical forest, waterfalls, caves, and green-yellowish paddy field. All of them creating beautiful sceneries that attract a lot of tourists, either local or international. (Note: Ngarai = Valley)
According to “Tambo”, Minangkabau traditional stories told through generations, Sianok name came from 2 words: Si (= Minang pronoun to mention somebody) and Anok (= Minang word for silent). So, in a whole, Ngarai Sianok means the valley of wise leader (silent can linked to wisdom and charismatic character, hence Wise).
In Minang folklore, once upon a time, there were outsiders came to Minangkabau land. One, Sang Sapurba (SS), was polite and kind. While the other one, Katik Muno (KM), was greedy and wanted to brutally dominate the peaceful Minangkabau land. Long story short, SS can finally defeat KM. The valley that once being cursed by KM then changing into a blessed land after SS won the fight. To honor him, the place is called: The valley of the wise leader. Or in short local language, Ngarai Sianok.
According to story, SS is descendant of infamous Islamic king/leader in the past, Iskandar Zulkarnain. Plus, he is a kind and charismatic figure, so people respect him much. He finally marry a Minangkabau princess and become a king with title of “Maharajadiraja”. Their descendants then became kings all around Melayu Kingdom (Indonesia, including modern Malaysia, Singapore, Brunei, and certain parts of nowadays Myanmar, Thailand, and Filipina).
Sihanoukville, or locally known as Krong Preah Sihanouk, is a coastal city in south-western part of Kingdom of Cambodia. It also become transit place to travel around various secluded islands nearby, such as Koh Rong, Koh Rong Sanloem, and more.
Sihanoukville is named according to the king who reign at the time it was built. The much respected king, Norodom Sihanouk, command city construction on 1955, parallel to construction of port in the same place for important transportation of logistic, oil, and more. The city official name, literally means: Kong (= province) Preah (= pure) Sihanouk (= king’s name). In a whole, it means: The Honorable Sihanouk Province.
King Sihanouk name itself comes from Sanskerta language, Siha (= lion) and Hanu (= jaw). By the way, lion seems to be important in the city. There is big Golden Lion Roundabout at city center, popular for direction finding to everything you need as traveller there.
So… they are not related. Just a coincidence phonetic words, which are very different by definition.