Preah Sihanouk Province

Preah Sihanouk Province is Cambodia's coastal hub — the province that gives the country its only direct access to the open Gulf of Thailand. The capital, Sihanoukville (Preah Sihanouk City), sits on a headland where the Cambodian lowlands reach the sea, and the offshore island chain stretching 80 km southwest — Koh Rong, Koh Rong Sanloem, Koh Tang, and a dozen smaller fragments — belongs to the same province. The tidal regime here is one of the most distinctive in Southeast Asia. The Gulf of Thailand is a semi-enclosed basin, open to the South China Sea at its southern end, and the restricted geometry dampens the tidal signal and skews the pattern away from the neat semidiurnal cycle seen on open-ocean coasts. Along the Preah Sihanouk coast, the regime is mixed diurnal: the tidal curve produces two unequal highs and two unequal lows each day through much of the year, but during the late southwest monsoon months — roughly June through September — the diurnal inequality becomes so pronounced that, on many days, only one high and one low are practically distinguishable. On those deeply diurnal days the total range at Sihanoukville can compress to 0.8 m or less, and the distinction between a morning high and an afternoon high nearly vanishes. The spring range in the more semidiurnal months (November through February) reaches approximately 1.2 m at Sihanoukville. The pattern shifts more than once across a single month: around new and full moon, the range is largest; around the quarter moons, the mixed character becomes more pronounced and the tidal curve can look more diurnal than semidiurnal. For practical activity planning, this variability is the key thing to understand. On some days the water rises and falls twice; on other days, especially in the monsoon season, the level rises once, stays nearly flat for most of the day, and drops once. The Department of Meteorology, Hydrology and Hydrography of Cambodia (DMHH) is the national authority for tide predictions and marine forecasts. The DMHH does not publish publicly accessible online tide prediction tables at the granularity that recreational users typically want, so Open-Meteo Marine gridded model predictions fill the practical gap for the province. For any safety-critical marine activity in the Gulf of Thailand from Cambodian waters, the DMHH is the authoritative contact.