Thailand

Dive Site: Secret Reef

5–12 mBeginner
© EsriSource: Esri, Maxar, Earthstar, GIS Community · Labels © Esri, HERE, Garmin, FAO, NOAA, USGS

Which liveaboards dive Secret Reef?

About Secret Reef

Secret Reef, nestled adjacent to Hin Raab South, is a captivating dive site close to Koh Chang, forming a unified, diverse underwater ecosystem. It is celebrated for its unique coral canyons, where whip corals gently sway and flower and spiny cabbage corals thrive, creating a macro paradise. This site boasts a shallow plateau at 5-6 meters and a maximum depth of 12 meters, making it ideal for Open Water divers, try dives, and those seeking a tranquil, uncrowded experience. The underwater topography includes distinct canyons that guide divers across the reef. Marine life encounters are frequent, with colorful nudibranchs adorning surfaces, blue-spotted stingrays resting on the sand, and moray eels peeking from their shelters. Barracudas are also spotted patrolling the reef edges, adding to the site's rich biodiversity. Divers can explore historical remnants, including an ancient teapot and scattered gunship bullets, providing a glimpse into the area's past. Combining Secret Reef with Hin Raab South allows for extended bottom time, making it perfect for thorough exploration and underwater photography.

Highlights

Hidden coral canyonMax depth 12 metersAncient teapot and bulletsVibrant coral gardensColorful nudibranchsBlue-spotted stingraysConnected to Hin Raab South

Season calendar

Best months to dive here
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Excellent
Good
Off-Season

Nov – Apr (Peak)

Best visibility 25–30m, calm Andaman Sea. Similan & Surin Islands open. Whale sharks and manta rays at Richelieu Rock.

May (Transition)

Similan season opening/closing. Variable conditions, occasional rain. Still good diving at coastal sites.

Jun – Oct (Monsoon)

SW Monsoon brings rough seas. Similan Islands CLOSED. Gulf coast (Koh Tao) still diveable Jun–Sep.

Dive site facts: Secret Reef

Depth
5–12 m
Current
Mild to none
Entry
Mooring line descent
Level
Open Water Diver, Try Dives
Dive type
Reef, macro, coral canyon
Region / port
Koh Chang, Eastern Gulf of Thailand
Coordinates
8.6886° N, 98.0460° E

Conditions & Currents

Secret Reef is generally known for its suitability for relaxed exploration, suggesting minimal to no significant currents. It offers conditions that are favorable for Open Water divers, implying that strong, challenging currents are not a predominant feature of the site. Calm conditions are expected, allowing for comfortable navigation through the coral canyons and over the shallow plateau. The site's nature permits extended bottom time, further indicating stable underwater environments without demanding current scenarios that would limit dive duration. Divers should still remain aware of any localized water movements typical of reef structures and consult with local dive guides regarding daily conditions.

Marine life & sighting chances

Dive profile & how the dive runs

Begin your dive with a descent along the mooring line, targeting a depth of approximately 12 meters. From this point, navigate the distinct coral canyons that meander across the reef, providing a natural guided path. Along the route, explore the vibrant coral gardens and search for unique site features such as an ancient teapot and scattered gunship bullets. The dive includes exploring a shallow plateau found at 5-6 meters, which is ideal for extending bottom time and allows for a gradual ascent. Conclude the dive by returning to the mooring line, where the safety stop is performed, ensuring a smooth and controlled ascent.

Underwater photography

Secret Reef is particularly rewarding for macro photography, given the abundance of colorful nudibranchs that dot the reef. A macro lens will allow you to capture intricate details of these tiny creatures, as well as the moray eels peeking from crevices and the vibrant coral polyps. For wider shots of the coral canyons and blue-spotted stingrays on the sandy bottom, a wide-angle or standard lens can be effective. Consider using a strobe or video lights to bring out the true colors of the corals and marine life, especially in deeper sections or within the canyons. Practice excellent buoyancy control to avoid disturbing delicate corals and to get close enough to small subjects without stirring up sediment.

Combine with nearby dive sites

Getting there & logistics

Access to Secret Reef is typically arranged through dive centers operating from Koh Chang, a popular island in the Eastern Gulf of Thailand. Koh Chang itself is part of the Mu Koh Chang National Marine Park, which is a prime diving region in the area. Divers usually fly into Bangkok's Suvarnabhumi International Airport (BKK), which serves as the main gateway to the country. From Bangkok, domestic travel options to Koh Chang are available, though specifics like flight duration or ferry connections are not detailed for this specific site. Day trips are common, as Secret Reef can be explored in combination with its adjacent site, Hin Raab South, allowing for a comprehensive two-dive day. Permit and park fees for the national marine park are generally required.

Safety & environment

While Secret Reef is considered suitable for Open Water divers, general dive safety protocols apply. Divers should ensure they have adequate insurance covering dive accidents and potential evacuation, as recompression chambers in Thailand are primarily located in major hubs like Phuket and Pattaya, implying a potentially distant evacuation in emergencies from Koh Chang. Site-specific hazards are minimal, given the shallow depths and generally mild currents, but divers should still maintain awareness of their surroundings within coral canyons. Adherence to a maximum depth of 12 meters is crucial. Always dive with a certified guide and follow their specific briefing regarding current conditions and site navigation. Good buoyancy control is essential to protect the delicate coral formations and avoid disturbing marine life or kicking up sediment.

Who it suits, and who it doesn't

Suited for

  • Open Water certified divers
  • Divers seeking relaxed exploration
  • Macro photography enthusiasts
  • Beginners and try divers
  • Those interested in marine history artifacts

Less suited for

  • Advanced divers seeking extreme depths
  • Divers primarily looking for strong currents and pelagic action
  • Snorkelers (due to site description)
  • Divers preferring extremely remote, untouched sites

FAQ

Secret Reef FAQ

What is the maximum depth at Secret Reef?
The maximum depth you will encounter at Secret Reef is 12 meters. This relatively shallow depth, combined with a plateau at 5-6 meters, makes the site very accessible and suitable for divers of various certification levels, including Open Water divers and those on try dives.
What marine life can I expect to see at Secret Reef?
Secret Reef is a macro paradise, renowned for its colorful nudibranchs which are frequently sighted. You can also expect to see blue-spotted stingrays resting on the sandy bottom, moray eels peering from crevices, and barracudas patrolling the edges of the reef. The site is also rich in diverse coral species.
Is Secret Reef suitable for beginner divers?
Yes, Secret Reef is highly suitable for beginner divers. With a maximum depth of just 12 meters and a shallow plateau, it's perfect for Open Water divers and even offers possibilities for try dives. The site's generally calm conditions and unique coral canyons provide an engaging yet relaxed introduction to diving.
Are there any unique features at Secret Reef?
Beyond its vibrant marine life and coral canyons, Secret Reef holds historical intrigue. Divers often discover a mysterious ancient teapot and scattered gunship bullets during their exploration. These unique artifacts add an extra layer of interest to the underwater adventure.
How is Secret Reef typically dived?
Dives at Secret Reef often begin with a descent along a mooring line to about 12 meters. Divers then follow the natural coral canyons over the reef, exploring the coral gardens and unique historical features. The shallow plateau allows for extended bottom time before returning to the mooring line for a safety stop. The site is often combined with Hin Raab South for a two-dive day.

Why dive Secret Reef from a liveaboard?

Secret Reef is one of Thailand's signature dive sites. A liveaboard sleeps you on the water and puts you in the water for three to four guided dives per day, including dawn and night dives that day-boat operators rarely offer. You skip the daily commute back to port and reach quieter, less-crowded sites in the same region on a single trip.

Below are the liveaboards that include Secret Reef on their Thailand itineraries.

Liveaboards diving Secret Reef

These liveaboards may visit Secret Reef on selected itineraries, the exact dive sites depend on departure, weather and conditions.

Mandarin Queen 9 liveaboard at Secret Reef

Mandarin Queen 9

Thailand

26 guests38 m
Dolphin Queen liveaboard at Secret Reef

Dolphin Queen

Thailand

20 guests24 m
Manta Queen 8 liveaboard at Secret Reef

Manta Queen 8

Thailand

24 guests
The Junk liveaboard at Secret Reef

The Junk

Thailand

18 guests33 m
Deep Andaman Queen liveaboard at Secret Reef

Deep Andaman Queen

Thailand

23 guests31 m
Camic liveaboard at Secret Reef

Camic

Thailand

14 guests24 m
Lapat liveaboard at Secret Reef

Lapat

Thailand

16 guests24 m
Explorer liveaboard at Secret Reef

Explorer

Thailand

16 guests25 m
Andaman liveaboard at Secret Reef

Andaman

Thailand

20 guests26 m
Stingray liveaboard at Secret Reef

Stingray

Thailand

8 guests24 m
Seatopia liveaboard at Secret Reef

Seatopia

Thailand

24 guests24 m
Bunmee 4 liveaboard at Secret Reef

Bunmee 4

Thailand

20 guests29 m

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12 liveaboards run the Secret Reef route.

Three to four guided dives a day on Secret Reef and the other signature sites in Thailand, sleeping right above the reef.