The Similan Islands are a small group of granite islands in the Andaman Sea, protected as a national marine park. They are known for clear water, white sand and big boulders both above and below the surface. They are a long way offshore from Khao Lak, so the trip is a full day or a multi-day liveaboard. The park is only open to visitors for part of the year, which makes timing the single most important planning decision.
Park season: when you can go
The Similan Islands National Park generally opens in the cool dry season and closes during the monsoon. As of 2026, the season is roughly mid-October or November to mid-May, but the exact opening and closing dates are set and announced by the Department of National Parks, and they can shift with weather or conservation decisions. Always check the official website of the Department of National Parks before you book.
Do not book non-refundable flights or hotels around a specific opening date. Check the official park announcement, and ask the operator what happens if the trip is cancelled for weather or park closure.
| Period | Status (approx.) | Notes |
|---|---|---|
| Mid-May to mid-Oct | Closed | Monsoon, rough seas |
| Late Oct to Nov | Opening period | Dates vary, early trips can be weather-dependent |
| Dec to Feb | Open, peak | Calmest seas, busiest and most expensive |
| Mar to mid-May | Open | Warm and calm, fewer crowds before closing |
How to get there
There is no regular public ferry. You travel with a licensed tour operator or a liveaboard boat from the Khao Lak coast.
- Thap Lamu pier is the main departure area for speedboat day trips and many liveaboards.
- Khao Lak pier areas serve some operators, depending on the boat.
- Transfer. Most trip packages include a hotel pickup in the Khao Lak area. Check the pickup time, which can be very early.
- Travel time. Speedboats typically take about 1 to 1.5 hours each way, depending on sea state and the island visited. Slower boats take longer.
If you are staying in Phuket, some operators offer pickups, but the road transfer adds 1.5 hours or more each way. Staying in Khao Lak makes for a shorter day. See where to stay in Khao Lak.
Day trip or liveaboard?
| Day trip | Liveaboard (multi-day) | |
|---|---|---|
| Time at the islands | A few hours across 2-4 stops | Many dives or snorkel stops, sunrise and sunset |
| Typical cost | THB 2,500-7,000 per person | THB 12,000-40,000+ per trip |
| Best for | First-timers, families, non-divers | Certified divers, photographers |
| Comfort | Speedboat, shared seating | Cabins, meals included |
| Weather risk | Cancellation on rough days | Itinerary can change on the water |
All prices are approximate, as of 2026. Check the current price and inclusions on the operator's own page, and confirm whether the national park fee is included.
What you can see
- Koh Similan (Island 8) is the largest and most visited, with a wide bay and a well-known boulder called Sail Rock on its shore. A short walk leads to a viewpoint over the bay.
- Koh Miang (Island 4) has beaches and a ranger station. It often hosts the lunch stop on day trips.
- Snorkel stops on the east side tend to have gentler conditions and coral, while the west side has bigger swells and boulder formations.
- Dive sites. The islands are known for granite boulders, swim-throughs and a chance to see reef fish and larger marine life. Dive conditions vary with season and current. Divers need the right certification and a registered operator.
- Other sites. Koh Bon and Koh Tachai are nearby islands that some liveaboards visit, with their own access rules. Check the park site for the status of each.
Island numbering and which islands are open to visitors can change. Stick with what the operator confirms.
Park rules and fees
As of 2026, visitors pay a national park entry fee on top of the boat trip. Foreign adult rates have been higher than Thai rates, and some operators include the fee while others add it at the pier. Check the official fee schedule at the Department of National Parks before you go.
Rules protect the reef. Typical ones include:
- No touching or standing on coral.
- No feeding fish, collecting shells or taking sand.
- Limits on visitor numbers and some areas closed for recovery.
- Rubbish must be taken back with you.
Use reef-safe sunscreen or wear a rash guard to reduce chemical load on the reef, and ask whether the operator limits group sizes at snorkel sites.
Sample day trip schedule
| Time (approx.) | Activity |
|---|---|
| 06:00-07:00 | Hotel pickup, drive to pier |
| 08:00 | Briefing and boarding |
| 09:30-10:30 | First snorkel stop |
| 11:30 | Second snorkel stop |
| 12:30 | Lunch on the beach or boat |
| 13:30 | Beach time, viewpoint walk |
| 15:00 | Return boat |
| 17:00 | Back at the pier, transfer to hotel |
Schedules vary by operator and weather.
Costs in detail
| Item | Approx. cost | Notes |
|---|---|---|
| Day trip package | THB 2,500-7,000 per person | Check whether park fee, lunch and snorkel gear are included |
| Park entry fee | Check official | Per person, may be paid separately |
| Snorkel gear rental | THB 0-300 | Often included |
| Liveaboard (3-4 days) | THB 12,000-40,000+ | Depends on boat and dive count |
| Hotel in Khao Lak | THB 700-5,000 per night | See the Khao Lak hub |
Prices are approximate as of 2026. Check the operator's own page for current prices.
What to bring
- Reef-safe sun protection and a hat.
- Rash guard or UV shirt.
- Quick-dry clothes and a towel.
- Dry bag for phone and valuables.
- Seasickness tablets if you are prone, taken before departure.
- Some cash for small purchases and tips.
- Passport or copy, as some operators ask for it at the pier.
Safety
Choose a licensed operator that provides life jackets, a briefing and a safety plan. Listen to the crew about currents. If you have a medical condition, check with your doctor before diving or taking a long speedboat ride. Keep travel insurance that covers water activities. For emergencies in Thailand dial 1669 for medical help, 191 for police and 1155 for the Tourist Police.
Plan your trip around the islands
- Read the Khao Lak travel guide for beach areas and transport.
- Compare neighbourhoods in where to stay in Khao Lak.
- Planning a bigger trip? See Phuket and Thailand best time by region.
- Thai version: สิมิลัน คู่มือ.
FAQ
When is the best month for the Similan Islands?
December to February usually has the calmest seas and best visibility, but also the most visitors. March to early May can be a good balance. Check the park opening dates for the current year.
Can I visit the Similan Islands from Phuket?
Yes, but the transfer to the pier adds around 1.5 hours or more each way. Staying in Khao Lak makes for a shorter day.
Is a day trip or liveaboard better for first-timers?
A day trip suits most first-timers, including non-divers. Liveaboards are mainly for certified divers who want multiple dives.
Is the national park fee included in the price?
It depends on the operator. Ask before booking, and check the official fee schedule from the Department of National Parks.
Is it safe for non-swimmers?
Life jackets are usually provided and shallow snorkel areas exist, but currents can be strong. Tell the crew you are a weak swimmer and stay close to the boat.
Can I stay overnight on the islands?
Limited park accommodation and camping have been available on some islands. Check the Department of National Parks website for current availability and booking rules.
Official sources and further reading
Prices, schedules and entry rules change. Figures here are approximate as of 2026; always confirm on the official or operator page before you book. Spotted something out of date? Tell us.
