Other marine life
Dugong
Dugong dugon
A sirenian — the only strictly marine herbivorous mammal — that grazes seagrass in shallow coastal waters across the Indo-Pacific. It is listed Vulnerable globally on the IUCN Red List; several subpopulations are assessed separately and more severely, with East Africa Critically Endangered and New Caledonia Endangered as of the 2022 assessments. Dugongs are slow-moving, shy of boats and engine noise, and are rarely encountered by scuba divers anywhere.
- Max size
- 3m, up to about 400kg
- Habitat
- Shallow coastal seagrass meadows, usually under 10m
Best places to dive with Dugong
| Month | Likelihood |
|---|---|
| January | rare |
| February | rare |
| March | rare |
| April | rare |
| May | rare |
| June | rare |
| July | rare |
| August | rare |
| September | rare |
| October | rare |
| November | rare |
| December | rare |
Con Dao holds what is likely Vietnam's last dugong population, and a 2023 survey by the Institute of Marine Environment and Resources estimated only about 12 animals remained. Their seagrass has collapsed — from over 329 hectares across 12 locations to two remaining areas, Con Son Bay and Bay Canh, by 2022 — and further deaths were reported in 2025. Divers essentially do not see them. Sightings are opportunistic ranger observations in shallow seagrass, not dive encounters, and the seagrass beds are inside strictly protected zones. Treat this as a conservation fact about Con Dao, not a reason to book a dive.
Sources & last checked
Checked August 2026
This is a researched draft, not yet human-verified. The seasonality and logistics are drawn from the sources below — confirm specifics (permits, fees, closures) with an operator before you book.
- HCM City eyes urgent solutions to conserve endangered dugong population in Con Dao — VietnamPlus (Vietnam News Agency)
- Con Dao IMMA factsheet — IUCN Marine Mammal Protected Areas Task Force
- IUCN Red List: Dugong Subpopulations Reassessed — Dugong & Seagrass Hub
Note on the data: The Vulnerable listing is the global assessment. Regional subpopulations carry separate, higher-risk listings, and Vietnam's animals are not covered by a published subpopulation assessment.