Overview

หมู่เกาะสิมิลัน • Mu Ko Similan National Park

The Similan Islands are consistently ranked among the world’s top dive destinations. Named from the Malay word “Sembilan” meaning “nine,” this archipelago of 11 granite islands rises from the Andaman Sea, 70 km off the coast of Phang Nga Province. Established as a national park in 1982, the 140 sq km marine protected area features exceptional underwater visibility (up to 40 meters), vibrant coral reefs, and diverse marine life including manta rays, whale sharks, and sea turtles.

The iconic Sail Rock (Hin Rua Bai) on Koh Similan is one of Thailand’s most photographed natural landmarks. The islands attract divers and snorkelers from around the world seeking crystal-clear waters, pristine white sand beaches, and encounters with spectacular marine life at sites like Richelieu Rock—Jacques Cousteau’s favorite and Thailand’s premier dive site.

For medical tourists visiting Thailand, the Similan Islands offer a breathtaking day trip experience during the dry season. However, the remote location (no mobile signal, no medical facilities) and boat access requirements make this destination best suited for those well into their recovery who can handle moderate physical activity.

Park fees, operating hours, and seasonal dates are subject to change. Verify current information through the official DNP website or your tour operator before booking.

History & Significance

Ancient Geology

The granite islands and underwater boulder formations that define the Similans were formed over 65 million years ago. These ancient rock structures create the dramatic underwater landscape—towering boulders, swim-throughs, and canyons—that makes the diving here world-famous.

Park Establishment

• 1982: Established as Mu Ko Similan National Park covering 128 sq km (9 islands)
• 1998: Expanded to include Koh Bon and Koh Tachai, bringing total to 11 islands and 140 sq km
• 2018: All overnight accommodation on islands permanently closed for ecosystem protection
• 2021: Chemical sunscreen ban implemented across all Thai marine parks
• 2025: E-ticket system made mandatory; stricter environmental enforcement

Coral Recovery

The Similan reefs suffered catastrophic bleaching events in 1998 and 2010, with approximately 90% coral mortality in some areas. By 2019, park authorities announced near-full recovery—a testament to the effectiveness of the annual 5-month closure and strict conservation measures. Some dive sites remain closed to allow continued regeneration.

The Name “Similan”

The name derives from “Sembilan,” a Yawi (Malay dialect) word meaning “nine”—referring to the original nine islands numbered 1-9 from south to north.

The Islands

The Original Nine

Additional Islands (Added 1998)

Natural Features & Ecology

Marine Ecosystem

The Similan Islands protect one of Thailand’s most biodiverse marine environments:

• Coral coverage: 500+ species of hard corals, extensive soft coral gardens
• Fish species: 2,000+ species of reef fish
• Visibility: 20-40 meters typical, best February-April
• Water temperature: 26-31°C depending on season

Coral Species

Hard Corals

• Staghorn coral (Acropora spp.)—fast-growing reef builders
• Table coral—distinctive flat formations
• Brain coral (Favia, Favites spp.)—massive dome-shaped colonies
• Elkhorn coral
• Massive corals (Porites spp.)—slow-growing, highly resilient
• Mushroom coral
• Foliose/leaf corals

Soft Corals

• Gorgonian sea fans—up to 2 meters wide, some of Thailand’s largest
• Sea whips
• Dendronephthya spp.—vibrant colors in reds, pinks, purples
• Carnation coral
• Bubble coral

Marine Life Highlights

Large Pelagics

• Manta rays: Frequently spotted at Koh Bon cleaning stations (November-May)
• Whale sharks: Appear February-May, peak sightings in April at Richelieu Rock
• Leopard sharks: Regular sightings at deep sites
• Whitetip reef sharks: Common at many dive sites

Sea Turtles

• Green sea turtle (Chelonia mydas)
• Hawksbill turtle (Eretmochelys imbricata)
• Ko Hu Yong (Island #1) is a protected nesting beach

Reef Fish

• Giant grouper
• Barracuda schools—sometimes hundreds strong
• Trevally
• Sweetlips
• Fusiliers—massive schools creating silver curtains
• Parrotfish
• Angelfish
• Clownfish
• Moray eels

Rare Finds

• Harlequin shrimp (Richelieu Rock)
• Seahorses (Richelieu Rock)
• Ghost pipefish
• Frogfish

Geological Features

• Granite boulder formations: Ancient rock structures creating underwater swim-throughs and canyons
• Sail Rock (Hin Rua Bai): Iconic boulder on Koh Similan, Thailand’s most photographed natural landmark
• Elephant Head Rock: Three massive granite boulders between Islands #7 and #8, resembling an elephant at low tide

Island Ecology

• Tropical rainforest vegetation on islands
• Pandanus (screw pine) and beach morning glory along shorelines
• Nicobar pigeon and white-bellied sea eagles
• Limited freshwater sources on islands

Activities & Experiences

Snorkeling

Note: No snorkeling at Richelieu Rock due to strong currents. All snorkeling is boat-based; equipment typically provided on tours.

Scuba Diving

Beginner-Friendly Sites

Advanced Sites

Certification Requirements:

• Open Water Diver (18m max): Most Similan sites
• Advanced Open Water (30m max): Recommended for Koh Bon, Ko Tachai, Richelieu Rock

Hiking

Note: The viewpoint trail is the only significant hiking on the islands. It’s steep and rocky—not recommended during recovery.

Photography

Best Locations:

• Sail Rock Viewpoint (Ko Similan)—sunrise/sunset
• Donald Duck Bay beach
• Underwater at Richelieu Rock (requires housing)

Gear Note: Underwater camera housing essential for diving/snorkeling photography. Drone flights require written DNP permission.

Wildlife Watching

• Sea turtle spotting: Snorkeling/diving throughout the park
• Manta ray encounters: Koh Bon, February-May
• Whale shark sightings: Richelieu Rock, February-May (peak April)
• Bird watching: Nicobar pigeon, white-bellied sea eagles on islands

Dive Sites in Detail

Richelieu Rock

Thailand’s Premier Dive Site

This horseshoe-shaped pinnacle in Surin Marine National Park (accessible on liveaboard trips) is consistently rated Thailand’s #1 dive site. Named by Jacques Cousteau in the 1980s for the rich red color of its soft corals—reminiscent of the robes of Cardinal Richelieu.

• Depth: 5-35m
• Current: Moderate to strong
• Highlights: Whale sharks (Feb-May), seahorses, harlequin shrimp, massive schools of barracuda and jacks, stunning soft coral coverage
• Best for: Experienced divers

Koh Bon

Manta Ray Hotspot

The premier location for manta ray encounters in the Similan area.

• Depth: 15-40m
• Current: Strongest in the park—advanced divers only
• Highlights: Manta ray cleaning stations, wall dive
• Best time: November-May for mantas

Elephant Head Rock

Underwater Adventure Playground

Named for its resemblance to an elephant at low tide, this site features dramatic underwater topography.

• Depth: 10-30m
• Current: Strong, drift dives
• Highlights: Massive granite boulders, swim-throughs, canyons
• Best for: Experienced divers comfortable with currents

For Medical Tourists

Physical Requirements Assessment

Post-Surgery Suitability

*Diving after LASIK requires specific clearance and waiting periods—consult your ophthalmologist. Diving is medically contraindicated for many conditions including recent surgery, cardiac issues, respiratory conditions, and ear problems. Always complete a diving medical questionnaire honestly and consult a dive physician if you have any health concerns.

Medical Advisory: The Similan Islands are a remote destination with NO medical facilities and NO mobile phone coverage. Emergency evacuation requires a 70+ minute boat transfer to the mainland, followed by road transport to hospital. Patients requiring immediate medical access should choose destinations closer to medical facilities. Always consult your doctor before any outdoor activities post-procedure.

Critical Safety Considerations

• No emergency medical facilities on islands
• No mobile phone signal—radio communication only
• Boat evacuation required for any medical emergency (minimum 70 minutes to pier)
• Diving adds risks: Decompression, ear barotrauma, exertion
• Heat exposure significant: Tropical sun on open water
• Speedboat can be rough: Impact on healing incisions, discomfort

Who Should NOT Visit

• Patients with recent surgery (any type)
• Cardiac patients (diving contraindicated)
• Those requiring regular medication access
• Anyone with mobility limitations
• Patients who may need emergency medical care

Who May Consider Visiting

• Patients 3-4+ weeks post minor procedures (with doctor approval)
• Those comfortable with no mobile signal for emergencies
• Visitors who will skip diving and limit to relaxed snorkeling/beach time
• People comfortable with potentially rough boat rides

Nearest Hospitals

Emergency from Islands: Radio to tour boat → Speedboat to Tab Lamu Pier (70+ min) → Road transport to hospital

Emergency Numbers:

• 1669: National Emergency Hotline
• 1199: Marine Police
• 1155: Tourist Police

Getting There

From Bangkok

1. Fly to Phuket International Airport (1 hour 20 minutes from Bangkok)
2. Transfer by road to Tab Lamu Pier (1.5-2 hours via Khao Lak)
3. Boat to Similan Islands (70-90 minutes by speedboat)

Tab Lamu Pier (Thap Lamu)

The departure point for virtually all Similan trips:

• Location: 13 km from Khao Lak town center, Phang Nga Province
• Facilities: Parking, shops, tour operator counters
• Travel from Khao Lak: 10-20 minutes via Route 4
• Alternative spellings: Thaplamu, Tapla Mu

Boat Options

Day Trip Details

• Cost: 1,800-3,500 THB depending on operator and inclusions
• Typical inclusions: Transfers, lunch, snorkeling gear, park fees (confirm before booking)
• Departure: Early morning (~6:00-8:00 AM from Khao Lak hotels)
• Return: Late afternoon (~4:00-5:00 PM)

Important Booking Requirements

• E-ticket mandatory: All visitors must purchase park entry through the official DNP QueQ app before 8:00 AM on travel day
• Passport required: Foreigner tickets require passport details
• Daily limit: 3,850 visitors maximum—book in advance during peak season
• Independent travel not permitted: Must join organized tour

Liveaboard Diving

Overview

Multi-day liveaboard trips offer the most immersive Similan experience, with access to remote sites (Richelieu Rock), night dives, and early morning dives not possible on day trips.

Season

October 15 - May 15 (same as park season)

Duration Options

• 2 days / 1 night
• 3 days / 3 nights
• 4 days / 4 nights (most popular)
• 5 days / 4 nights
• Up to 10 days

Price Range (per day)

Typical Itinerary

Day 1: Depart Tab Lamu Pier (afternoon/evening) → Cruise to Similans overnight Days 2-3: Similan sites → Koh Bon → Koh Tachai Day 4: Richelieu Rock → Return to pier

Booking Tips

• Book 2-3 months in advance for peak season (December-April)
• National park fees typically paid separately in cash onboard
• Nitrox (enriched air) available on many boats
• Confirm certification requirements for itinerary

Practical Tips

What to Pack

Essential:

• Reef-safe mineral sunscreen (zinc oxide/titanium dioxide)
• Rash guard or 3mm wetsuit (sun protection + jellyfish)
• Underwater camera with housing
• Dry bag for electronics
• Motion sickness medication (if prone)
• Cash (THB) for tips and welfare shop

For Divers:

• Certification card and logbook
• Personal mask/fins if preferred
• Dive computer (or rent)

For Recovery Patients:

• Hospital contact card
• Any prescribed medications
• Cooling towel

What NOT to Bring

Water Conditions by Month

Special Phenomena

“Green Monster”: Occasional cold water upwellings (down to 21°C) reduce visibility but attract unusual marine life. Notable events occurred in December 2019 and late 2023-early 2024.

Coral Spawning: Typically occurs 3-5 days after the full moon in April—a spectacular underwater event.

Environmental Responsibility

Reef Protection Rules

• Never touch coral—even dead coral may harbor life
• Never stand on coral—use sandy areas only
• Maintain neutral buoyancy when diving
• Keep fins away from reef structures
• No flash photography of marine life at night
• Maintain safe distance from all marine life

Sunscreen Ban

Since August 2021, chemical sunscreens are banned in all Thai marine parks:

Banned Ingredients:

• Oxybenzone
• Octinoxate
• 4-Methylbenzylidene Camphor
• Butylparaben
• Homosalate
• Octocrylene

Allowed: Mineral-based sunscreen with zinc oxide or titanium dioxide

Penalty: Up to 100,000 THB fine

Plastic-Free Policy

Single-use plastics and styrofoam containers are prohibited. Bring reusable water bottles—refill stations available on most tour boats.

Ethical Wildlife Interaction

• No feeding fish—disrupts natural behavior
• No chasing marine life—let animals approach you
• No touching turtles or rays
• Keep distance from whale sharks (minimum 3m recommended)
• Never collect shells, coral, or marine life

Conservation Measures

The park implements strict protection:

• Daily visitor caps: 3,850 people maximum
• 5-month annual closure: May 16 - October 14 for ecosystem recovery
• Closed dive sites: East of Eden, partially Anita’s Reef (coral regeneration)
• Mooring buoy system: Prevents anchor damage to reefs
• Ranger patrols: Active monitoring and enforcement

Seasonal Guide

Peak Season (December - April)

• Best overall conditions for diving and snorkeling
• Calmest seas, easiest boat transfers
• Highest visibility (30-40m in Feb-Apr)
• Warmest water (29-32°C)
• Wildlife: Manta rays active; whale sharks Feb-May
• Crowds: Highest—book in advance
• Prices: Peak rates

Shoulder Season (October - November)

• Season opening October 15
• Conditions variable, improving through November
• Cooler water (21-27°C) possible in October
• Reduced visibility but good for large pelagics
• Fewer crowds
• Lower prices

Closed Season (May 16 - October 14)

• Complete closure—no access permitted
• Southwest Monsoon brings rough seas, heavy rain
• Essential for ecosystem recovery
• All boats return to mainland

Nearby Attractions

Nature Sites

Beaches

• Khao Lak Beach: Long sandy beach, sunset views, base for Similan trips
• Bang Niang Beach: Quieter beach north of Khao Lak

Cultural Sites

• Tsunami Memorial (Police Boat 813): Khao Lak—remembrance of 2004 disaster

Therapeutic

• Klong Thom Hot Springs: Krabi Province (~200 km south)—natural hot spring pools in forest setting

Useful Thai Phrases

Contact Information

Park Headquarters

• Address: Mu Ko Similan National Park, 93 Moo 5, Lam Kaen Sub-district, Thai Mueang District, Phang-Nga Province 82210
• Phone: +66 76 453 272 / +66 76 453 273
• Email: np_similan@hotmail.com
• Website: https://portal.dnp.go.th/

Emergency Numbers

• 1669: National Emergency Hotline
• 1199: Marine Police
• 1155: Tourist Police

Park Entry Tickets

• E-ticket System: QueQ App (mandatory)
• Booking deadline: Before 8:00 AM on travel day
• Passport required for foreigner tickets