Diving in Thailand in December: December kicks off Thailand’s peak season, when the tourist action ramps up, especially along the Andaman coast.
Calm seas, clear skies, and warm weather make this month perfect for underwater adventures. Air temperatures average between 27-32 °C, while the water stays warm at around 28-29 °C. Rainfall is minimal, giving divers ideal visibility that often ranges from 20 to 40 meters.
Because of these conditions, both beginners and seasoned divers can enjoy more stable currents and excellent dive opportunities.
In addition, December aligns with Thailand’s vibrant holiday season, adding to the excitement of any trip.
Andaman Sea vs. Gulf of Thailand
Why Choose the Andaman Sea
The Andaman Sea, on Thailand’s west coast, is widely considered the top diving area in December.
Sites like the Similan Islands, Surin Islands, and Richelieu Rock offer coral gardens, thriving marine life, and clear water. Dive operators and liveaboard trips are in full swing in December, catering to all experience levels.
This region also offers a wide range of accommodation options and also day-trip packages.
Gulf of Thailand Conditions
In contrast, the Gulf of Thailand, which includes Koh Tao, Koh Samui, and Koh Phangan, faces the tail end of the monsoon season. Seas can be a little more rough, and visibility is often reduced. Although diving is possible, conditions are more inconsistent compared to the Andaman side.
For optimal diving experiences in December, most divers head to the west coast.
Top Dive Destinations for December
Northern Andaman Sea
Similan Islands
The Similan Islands are famous for large granite boulders, swim-throughs, and colorful reefs. December provides great visibility and mild currents. Whale sharks and manta rays are are known in December, making the Similans ideal for liveaboard trips.
Richelieu Rock
Richelieu Rock is one of Thailand’s most celebrated dive sites. The reef teems with barracudas, large groupers, and vibrant macro life. December’s calmer seas and bright water conditions create perfect settings for underwater photography.
Surin Islands
The Surin Islands offer shallow coral gardens, pristine reefs, and diverse marine species. Napoleon wrasse, bumphead parrotfish, and reef sharks are often spotted here. These islands are excellent for divers seeking a mix of easy and moderate dives.
Ready for adventure?
The following of our liveaboard itineraries head out to the North Andaman in December –
Southern Andaman Sea
Phuket and Phi Phi Islands
Phuket and Phi Phi are convenient hubs for day diving. Popular sites such as Shark Point, King Cruiser Wreck, and Anemone Reef offer encounters with leopard sharks, sea turtles, and colorful fish schools.
Hin Daeng and Hin Muang
Located near Koh Lanta, these more advanced sites are known for deep walls and purple corals. Manta rays and whale sharks are spotted at these sites during December. While currents can be more challenging, the reward is incredible marine life.
Ready to dive in?
The following liveaboard itinerary heads to the South Andaman in December –
Marine Life You Can See in December
December is one of the best months for spotting large pelagic species. Whale sharks, manta rays, and reef sharks are seen at the Similans, Surin Islands, and Richelieu Rock. Additionally, macro enthusiasts will enjoy nudibranchs, seahorses, and rare shrimp among the reefs.
What to Expect Underwater
Visibility: 20-40 m in the Andaman Sea, less in the Gulf.
Water Temperature: 28-29 °C on average, with thermoclines dropping to 24-25 °C.
Currents: Generally mild, though more challenging currents can occur at sites like Hin Muang.
Travel Planning Tips
Travel Planning Tips
Book Early
December is running in to high season, so book early for liveaboards and resorts.
Pick Trusted Operators
Choose dive centers with certified instructors and a strong safety record. Reputable operators maintain quality equipment and provide guidance for all experience levels.
What Gear to Pack
A 3 mm wetsuit is usually sufficient. Bring reef-safe sunscreen, a dive torch for night dives, and seasickness medication if you plan on joining a liveaboard trip (if not already provided).
Check out our packing article here for some ideas and reminders for what to pack (with downloadable packing list too) –
Day Trips vs. Liveaboards
Liveaboards (3-10 nights) allow access to remote sites and multiple daily dives. Day trips from Phuket or Phi Phi are better for those who are on a shorter time frame, although less comfortable overall.
Marine Parks and Conservation
Similan and Surin national parks open from mid-October to mid-May. December is within the prime diving window, and daily visitor limits protect coral ecosystems. Always follow eco-friendly guidelines such as avoiding coral contact, using reef-safe products, and respecting marine life.
Alternative Dive Options
The Gulf of Thailand remains an option for budget divers, particularly around Koh Tao. However, visibility is often less reliable than the Andaman coast. If you are after consistent conditions, the west coast remains the better choice.
FAQs
1. Is December the best month for diving in Thailand?
December is a great month for diving in Thailand and offers warm water, clear visibility, and calm seas, especially along the Andaman coast.
2. Can I dive in the Gulf of Thailand in December?
Yes, but conditions are less predictable due to lingering monsoon effects. The Andaman coast is preferred.
3. What marine life can I expect?
In December, divers may encounter manta rays, leopard sharks, and blacktip reef sharks, along with hawksbill and green turtles. Reefs are home to cuttlefish, giant trevally, barracuda, batfish, and blue-spotted stingrays. You’ll also see moray eels, lionfish, nudibranchs, and occasionally frogfish or ghost pipefish. If conditions are right, even a whale shark may pass by.
4. What gear should I bring?
A 3 mm wetsuit (although some dive in just board shorts and rash vest), dive torch, reef-safe sunscreen, and seasickness tablets are recommended (if not provided already).
For more on what to pack, check out our article here – What to Pack for Your Liveaboard Adventure in Thailand
5. Are dive sites crowded in December?
December is running into peak season, so some dive areas may be busier. When booking a liveaboard with The Junk Liveaboards, our on board teams do the best they can to find you the best conditions, with the fewest crowds as possible.
Booking early for peak season ensures availability for your next adventure.
