Southeast Vietnam

Southeast Vietnam — the coastal arc running south from Ho Chi Minh City to the Ca Mau Peninsula tip — opens onto the South China Sea, one of the world's largest marginal seas and a basin with a tidal character that surprises most visitors from Atlantic or Pacific coasts. The South China Sea produces a mixed, predominantly diurnal tide: in much of southern Vietnam, including Vung Tau, there is often one dominant high water and one dominant low water per day, with a secondary smaller oscillation. Spring range at Vung Tau runs 3.0 to 3.5 metres — large enough to matter operationally — but the diurnal inequality means the two highs and two lows (when they appear) are substantially different in height. On some days the secondary high is so small as to barely register. The physical geography of the southeast region is defined by the Mekong Delta to the south and west: the nine distributaries of the Mekong reach the sea between Vung Tau and the Ca Mau tip, depositing vast quantities of sediment and creating a low, flat, mangrove-fringed coastline unlike the sandy beaches and rocky headlands of central Vietnam. Vung Tau itself sits on a peninsula projecting into the sea at the mouth of the Saigon River, which made it the natural access point for the city now called Ho Chi Minh City — 125 kilometres by road, 90 minutes by hydrofoil on a direct sea route that became standard commute infrastructure for the offshore oil industry based in Vung Tau. The petroleum industry presence shapes the city: offshore supply vessels, crew boats, and drill ship support operations run from the port, and the maritime traffic in the approaches is dense. For visitors, the practical distinction is between Back Beach (Bãi Sau) on the open South China Sea face and Front Beach (Bãi Trước) on the sheltered western side of the peninsula facing the Saigon River approaches — different swell exposure, different water clarity, and different tidal effects on the foreshore width.