Scuba Diving at Hin Daeng & Hin Muang

Diving at Hin Daeng & Hin Muang

Hin Daeng and Hin Muang are two open-ocean pinnacles sitting around 55 to 70 km south of Koh Lanta, far enough offshore that there's no land in sight on the descent. They're the deepest, wildest dives in the Thai Andaman, with walls dropping past 60 m (197 ft), schools of barracuda working the blue, and the most reliable oceanic manta encounters in the country. The IUCN has designated the site an Important Shark and Ray Area for oceanic mantas. About 25 percent of all Thai oceanic manta records come from Hin Daeng alone, and 68 percent of those sightings fall between February and April.

This is not a beginner trip. Both pinnacles require Advanced Open Water certification at most operators, the crossing is fully exposed (and frequently cancelled by weather), and the dive profiles tempt you below recreational limits. Currents are real and can shift mid-dive. Strong thermoclines from internal-wave mixing in the Andaman bring colder, nutrient-rich water up the walls. That's also what brings the mantas.

The reward is two of the most spectacular dives in Thailand on the same boat. Hin Daeng ("Red Rock") breaks the surface with red-coral walls dropping into blue. Hin Muang ("Purple Rock") sits fully submerged and runs Thailand's tallest pinnacle wall, carpeted in purple soft coral from 8 m (26 ft) to 60 m (197 ft). Most day trips run a 2-tank dive on one site each, with an optional third dive at Koh Haa on the return.

Top dive sites at Hin Daeng & Hin Muang

The top dive sites at Hin Daeng & Hin Muang are the two pinnacles themselves. They sit around 200 m apart per the IUCN ISRA factsheet (some operators describe the gap as longer), linked by a 40 m submerged ridge, and both fall inside Mu Ko Lanta National Park. The standard plan is one dive on each, in whichever order the captain reads the current.

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Hin Daeng ("Red Rock")

Hin Daeng is the only one of the two pinnacles that breaks the surface, so you can spot it from the boat. The dive itself is a sloping descent along red-soft-coral walls that drop to a sandy plateau around 45 to 50 m (148 to 164 ft) on the north side and steepen toward 70 m+ (230 ft+) on the southern face. The headliner is the manta cleaning station on the north outcrop, separated from the main reef by a sand channel. Mantas come in to be cleaned by wrasse on the coral heads, often hovering for minutes at a time. Whale sharks pass through the same area during plankton-rich periods. On a quieter dive you'll still get schooling barracuda, giant trevally, grey reef sharks, and dogtooth tuna patrolling the deeper edges.

• Depth: 5–50+ m (16–164+ ft) on the main wall; southern face drops past 70 m (230 ft)
• Visibility: 20–30 m (66–98 ft), occasionally 40 m (131 ft)
• Current: Moderate to strong; can shift mid-dive
• Level: Advanced Open Water
• Key species: Oceanic manta ray, whale shark, grey reef shark, schooling barracuda, giant trevally, dogtooth tuna

Hin Muang ("Purple Rock")

Hin Muang is fully submerged. The shallowest point sits around 8 m (26 ft) below the surface, with an east-to-west ridge that drops sharply on every side. The northern slope falls to 45 m (148 ft), the western pinnacle hits around 24 m (79 ft), and the southern wall plunges past 60 m (197 ft), generally cited as Thailand's tallest submerged pinnacle wall. The whole structure is wrapped in purple soft coral, with red gorgonians and black corals in the deeper sections. Buoyancy matters here: the wall is photogenic enough that divers routinely chase the perfect shot below 30 m without noticing. Manta and whale shark sightings carry over from Hin Daeng, and you'll usually see schooling jacks and big-eye trevally moving along the ridge.

• Depth: 8–60+ m (26–197+ ft); southern wall to 70 m (230 ft)
• Visibility: 20–30 m (66–98 ft), occasionally 40 m (131 ft)
• Current: Moderate to strong; ridge orientation means the current direction shapes the dive plan
• Level: Advanced Open Water (Deep Diver specialty recommended)
• Key species: Oceanic manta ray, whale shark, big-eye trevally, schooling jacks, eagle ray, marble ray, harlequin shrimp

Best time to dive Hin Daeng & Hin Muang

The best time to dive Hin Daeng & Hin Muang is February to April, when manta activity peaks, whale sharks show up, and the sea state is at its calmest. The sites are reachable from mid-October through mid-May; outside that window the southwest monsoon shuts down the crossing and the national park closes the area entirely from 16 May to 31 October.

If your trip can flex by a week, time it for late February through early April. Even within the open season, individual day trips get cancelled when sea state is poor, so front-load your schedule.

Diving conditions

Diving conditions at Hin Daeng & Hin Muang are the most demanding in the Andaman. There's no land protection, no nearby reef to duck behind, and the currents are open-ocean. Plan deep, dive shallower than you think.

Marine life at Hin Daeng & Hin Muang

Marine life at Hin Daeng & Hin Muang is what makes the long crossing worth it. The headliners are big animals working an open-water aggregation site, and the deeper soft corals along Hin Muang have held up better than shallow hard-coral reefs during the bleaching events that have hit the wider Andaman.

Oceanic mantas: October to May, peak February to April, especially around Hin Daeng's north cleaning station

Hin Daeng is the most reliable manta site in Thailand. The IUCN ISRA dataset has logged 141 encounters with 118 individual oceanic mantas since 2006 via citizen science. Roughly 68 percent of sightings fall between February and April. The cleaning station on the separated north outcrop is the focus. Mantas hold steady there for minutes, sometimes stacked two or three at a time.

Whale sharks: February to May, peak February to April, especially around Hin Daeng and Hin Muang

Whale shark encounters here are chance events rather than predictable visits, but the peak window mirrors the manta season. Sources vary slightly on the exact range; February through April is the strongest call, with May sightings on the right plankton conditions.

Grey reef sharks and leopard sharks: year-round in the open season, especially around Hin Daeng's southern face and the sand plateau

Grey reef sharks patrol the deeper edges of both pinnacles. Leopard sharks rest on the sand at the base of Hin Daeng during the day, usually in the 25 to 35 m (82 to 115 ft) range. Eagle rays and marble rays show up on the sand patches between the pinnacles.

A word on coral status: both pinnacles have been hit by repeated bleaching (1998, 2010, 2016, and again in 2024). Andaman reefs as a whole now average around 35 percent coral cover, down significantly from earlier decades. The deep soft corals that define Hin Muang have fared better than shallow hard corals thanks to depth and temperature buffering, but operator copy still calling the sites "pristine" is selling an older picture. These dives are absolutely worth doing. They've just changed.

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Practical information

Dive prices at Hin Daeng & Hin Muang

• 2-tank day trip from Koh Lanta: THB 3,950 – 4,500 (USD 115 – 130), including gear, guide and lunch
• Speedboat supplement (where charged separately): Around THB 1,200
• Marine park fee: Around THB 600 per diving day, paid in cash on the boat
• Optional third dive (typically Koh Haa on the return): Around THB 600 extra
• Liveaboard inclusion (southern Andaman itinerary, 4 – 5 nights from Phuket/Khao Lak): From around USD 900

Getting to Hin Daeng & Hin Muang

The pinnacles are reachable two ways. Day trips run from Koh Lanta by speedboat, taking around 75 minutes to 2 hours each way depending on the operator's boat and the sea state. Lanta is the closest, fastest, and cheapest base. Operators including Lanta Diver, Dive & Relax, Phoenix Divers, Blue Planet Divers, Hidden Depths Diving, Scubafish, and Go Dive Lanta run the trip during the open season. Departures are typically 07:00 to 08:00 from Saladan or one of the southern Lanta piers, with return mid-to-late afternoon.

The alternative is a southern Andaman liveaboard from Phuket (Chalong Pier) or Khao Lak, usually 4 to 5 nights, with Hin Daeng and Hin Muang on the itinerary alongside Koh Haa, the Phi Phi area, and Shark Point.

Hyperbaric chamber

The nearest recompression facility is the SSS Phuket Hyperbaric Chamber at Bangkok Hospital Siriroj. The realistic medevac route from Hin Daeng is the boat ride back to Lanta (90 minutes to 2.5 hours) plus a 4-hour ground-and-ferry transfer to Phuket, or air ambulance via Krabi for a real emergency. Build the chamber distance into your dive plan: stay shallower than you think, and don't push the wall at Hin Muang because it's there.