Marine Life Calendar: when to see what in SE Asia
Browse 12 marine species by month and dive location across Thailand, Indonesia and the Philippines. Whale shark, manta, mola mola, hammerhead season windows.
Browse by month
Species
Sighting probability: "Best months" mean peak window, not guaranteed. Even at Richelieu in March, whale shark sightings run ~1 in 8 trips. Data combines peer-reviewed sighting databases (OBIS), dive operator logs and editor first-hand records over 2010-2025.
Disclaimer: This tool is an educational aid. It is not a substitute for a personal dive computer, proper certification, or current medical advice. Plan dives conservatively and consult a dive professional when in doubt. Emergency: DAN Asia-Pacific +61-8-8212-9242.
Frequently asked questions
Is a 'year-round' species really seen every dive?
No — year-round means sightings happen in every month, not on every dive. Reef sharks, turtles, frogfish are 'year-round but variable' depending on site condition, time of day, and luck.
Why doesn't this calendar include Maldives / Red Sea / Caribbean?
We focus on Southeast Asia where the editor has first-hand sighting data. Maldives/Red Sea/Caribbean are covered by region-specific guides we'd point you to: Maldives Atolls, DAN/Underwater360 sighting databases.
How does climate change affect these windows?
Some patterns are shifting — Nusa Penida mola sightings now extend slightly later (Oct vs traditional end-Sep) per local operator logs. Whale shark windows at Sail Rock have shown some compression. We update this calendar annually.
Can I report a sighting to add to the data?
Direct sighting reports go to OBIS, Atlas of Living Australia, or species-specific projects like Wildbook for Whale Sharks. We use these aggregated sources, not direct user reports.