Dive Site: Koh Haa — The Chimney

About Koh Haa — The Chimney

Koh Haa, meaning "five islands" in Thai, is a stunning archipelago within the Koh Lanta National Park, known for its pristine waters and diverse dive sites. The Chimney, specifically located on Koh Haa Island No. 1, presents a captivating underwater labyrinth. This site features a unique cavern system, including a narrow vertical tunnel that challenges divers with its confined ascent. The topography of The Chimney site encompasses large boulders creating numerous swim-throughs and crevices, alongside beautiful soft coral gardens. Depths range from shallow areas suitable for beginners to deeper sections reaching 30 meters, accommodating various skill levels. The highlight is an eerie underwater tunnel commencing at 17 meters, which gradually narrows before ascending into a chamber at 5 meters. Marine life here is abundant and varied, with common sightings of curious batfish, hawksbill turtles, and large shoals of snapper. The site also boasts numerous nudibranchs, moray eels, and lionfish. While larger pelagics like whale sharks and manta rays are occasionally seen in the broader Koh Haa area, The Chimney primarily offers rich macro life and vibrant reef inhabitants. Experiencing The Chimney involves careful buoyancy control and gentle finning to navigate its intricate passages. The dive promises excellent photographic opportunities, especially within the cavern where light filters down, creating an ethereal glow around cavern sweepers. Despite its adventurous nature, the site is accessible for advanced divers who appreciate unique underwater topography and diverse reef ecosystems.

Dive site facts: Koh Haa — The Chimney

Depth

5–30 m

Current

Weak to Medium

Visibility

5–30 m

Water temperature

27–31 °C

Entry

Liveaboard or dayboat

Level

Advanced Divers

Dive type

Cave, Reef, Coral reef, Swim-through

Region / port

Koh Lanta / Andaman Sea

Coordinates

7.308, 98.972

Conditions & Currents

Currents at Koh Haa, including The Chimney, are generally described as weak to medium, and surface conditions are usually calm. While suitable for various dive levels, navigating the narrow chimney requires precise buoyancy control and gentle finning to avoid disturbing the environment or other divers. Visibility typically ranges from 5 to 30 meters, depending on seasonal factors and runoff, though it can be consistently excellent during peak season. Divers should be mindful of boat traffic, especially during day trips, though liveaboards often enjoy quieter dive times. No significant thermoclines or surge are typically reported for this site.

Marine life & sighting chances

Batfish

common

Hawksbill turtle

common

Snapper

common

Nudibranch

common

Moray eel

common

Lionfish

common

Tigertail seahorse

occasional

Cavern sweepers

common

Clownfish

common

Scorpionfish

occasional

Whale shark

December to April · rare

Manta ray

December to April · rare

Dive profile & how the dive runs

Your dive at The Chimney typically begins with a descent to the south side of Koh Haa Island No. 1, where large boulders form numerous swim-throughs and crevices. You'll explore these formations, observing the vibrant soft corals and diverse reef fish. The main highlight is the entry into the cavern system, starting around 17 meters. You will navigate a tunnel that gradually narrows and ascends. Exiting the chimney at approximately 5 meters, you'll find yourself in a shallow chamber filled with cavern sweepers, offering excellent photographic opportunities. After exploring the shallow reef, you can proceed with your safety stop before ascending to the surface, maintaining careful buoyancy throughout the dive.

Underwater photography

The Chimney at Koh Haa offers unique photographic challenges and rewards, particularly within its cavern system. A wide-angle lens is ideal for capturing the grandeur of the swim-throughs, the light filtering into the chambers, and the schools of cavern sweepers. For macro enthusiasts, a macro lens will be invaluable for documenting the diverse nudibranchs, seahorses, and intricate soft corals found along the walls and crevices. Buoyancy control is paramount, especially when navigating the narrow chimney, to avoid stirring up silt or damaging delicate corals. Using strobes can enhance the vibrant colors of the soft corals and marine life, while careful lighting can create dramatic effects with the ambient light inside the caverns. Always maintain a respectful distance from marine life and avoid touching any part of the reef.

Combine with nearby dive sites

• Koh Haa — Lagoon

  A shallow, protected site ideal for all levels, known for yellow boxfish and hawksbill turtles.

• Hin Daeng

  A deeper pinnacle dive with strong currents, famous for soft corals and potential pelagic sightings.

• Hin Muang

  Adjacent to Hin Daeng, known for vibrant purple corals and frequent sightings of manta rays and whale sharks.

• Koh Phi Phi — Bida Nok

  Offers diverse marine life, including leopard sharks and schools of fish around rock formations.

• Koh Phi Phi — Bida Nai

  Features walls, caves, and swim-throughs with opportunities to see blacktip reef sharks.

• Koh Bon

  Known for its cleaning station, attracting manta rays, and offering vibrant coral walls.

Getting there & logistics

Access to Koh Haa, including The Chimney, is typically via day trip boats or liveaboards departing from Koh Lanta or Phuket. Koh Lanta is a primary departure point, with speedboat transfers reducing travel time to 45–60 minutes. Phuket also offers day trips, though these can be full-day excursions. The nearest major airport is Krabi International Airport (KBV), followed by a transfer to Koh Lanta. Some itineraries also connect via Phuket International Airport (HKT). Dive trips to Koh Haa are often combined with other sites in the Mu Ko Lanta National Park, such as Hin Daeng and Hin Muang. The national park is officially open from October 15th to May 15th each year, with liveaboards offering multi-day trips for a more immersive experience. Park entry fees are usually included in dive trip packages.

Safety & environment

Diving at Koh Haa's Chimney requires advanced diving skills, particularly excellent buoyancy control, due to the confined spaces and delicate environment within the cavern system. Divers should always follow their dive guide's instructions and maintain a safe distance from rock formations and marine life. The nearest recompression chamber is located in Phuket, highlighting the importance of cautious diving practices and adequate dive insurance coverage that includes emergency evacuation. While currents are generally mild, conditions can vary, so stay aware of your surroundings. Always ensure your equipment is well-maintained and conduct thorough buddy checks before each dive. Respecting marine park regulations, such as not touching or collecting marine organisms, is crucial for preserving this unique ecosystem.

Who it suits — and who it doesn't

FAQ

Koh Haa — The Chimney FAQ

Liveaboards diving Koh Haa — The Chimney

These liveaboards may visit Koh Haa — The Chimney on selected itineraries — the exact dive sites depend on departure, weather and conditions.

Mandarin Queen 9

Thailand

26 guests37.5 m

Manta Queen 8

Thailand

24 guests

$127/day

The Junk

Thailand

18 guests33 m

$163/day

Deep Andaman Queen

Thailand

23 guests30.5 m

$194/day

Explorer

Thailand

16 guests25 m

$150/day

Andaman

Thailand

20 guests26 m

$108/day

Stingray

Thailand

8 guests24 m

$245/day

Seatopia

Thailand

24 guests24 m