Similan Islands Guide: Day Trips, Snorkeling & Diving in Thailand's Best Marine Park

Why the Similan Islands stand out

The Similan Islands - officially Mu Ko Similan National Park - are consistently ranked among the top ten dive destinations in Asia, and for good reason. Nine islands of ancient granite rise from the Andaman Sea about 84 km northwest of Phuket. Above the waterline, you get white-sand beaches, boulder-strewn headlands, and clear horizons. Below it, visibility regularly reaches 20–30 metres over coral gardens that host leopard sharks, hawksbill turtles, and seasonal manta rays.

The catch is the window. The park opens mid-October and closes mid-May. For roughly five months each year, the Andaman monsoon makes the crossing unsafe and the authorities shut access entirely. If your travel dates fall outside this window, no amount of money or persistence will get you there.

Season and timing

Open season: mid-October to mid-May
Best visibility: November through April
Peak crowds: December through February
Best value: October–November and April–May (quieter, good conditions, lower prices)

During December and January, tour boats cluster the best sites and day-trip numbers can be significant. If you are flexible, an early-season visit in late October or November gives solid conditions with noticeably fewer boats.

National park fees

The entrance fee for foreign adult visitors is approximately 500 THB as of 2026. Children pay around 300 THB. Thai nationals pay 100 THB. The fee is collected at the park office on Island 4 (Ko Miang) - it is not included in tour prices, so budget for it separately. Cash only at the pier.

Getting there: Khao Lak vs Phuket

From Khao Lak (~1 hour)

Khao Lak is the nearest mainland access point, roughly 60 km south of the islands. Speedboats depart Tab Lamu Pier or Bang Niang Pier and reach the first islands in about 50–70 minutes depending on sea conditions. This is the preferred departure point for day trips, liveaboards, and most experienced operators. The shorter crossing means more time in the water.

If you are based in Phuket and want to do a Khao Lak departure, it’s around a 1.5–2 hour drive north. Many tour packages include a hotel pickup from Phuket and transfer to Khao Lak pier - check before booking whether this is included.

From Phuket (~2.5 hours)

Speedboat day trips depart from Phuket’s Ao Po Grand Marina or Chalong Pier. Journey time is roughly 2.5 hours each way, meaning you spend five hours traveling for a day trip. Some operators use larger catamarans which are more comfortable but slower.

If you are staying in Phuket, the convenience is obvious - no early-morning transfer north. The tradeoff is significantly less time at the islands. Arrive at the site around 11am, depart by 3pm: that’s a tight window for diving and snorkeling.

Bottom line: Khao Lak is better for the experience. Phuket works if you are already there and the travel north isn’t practical. See our Phuket island guide for what else to do while you’re based there.

Recommended tour operators

Seastar Andaman (from ~3,500 THB)

One of the most established operators running out of Khao Lak, Seastar Andaman has a strong reputation for small group sizes and well-briefed dive guides. Day-trip packages from approximately 3,500 THB include equipment, a dive guide for certified divers, snorkel gear, lunch, and national park fee. Liveaboard trips (2–4 nights) run from around 12,000–20,000 THB depending on cabin class and itinerary. Book well in advance for peak season.

Love Andaman (from ~3,200 THB)

Another Khao Lak-based operator, Love Andaman runs speedboat day trips from around 3,200 THB. They cater to both snorkelers and divers and typically include equipment rental, lunch, and a park fee subsidy (verify current inclusions at booking). Their boats hold moderate group sizes and they cover the same main sites as most operators.

Budget operators via Phuket

Several large booking aggregators offer Phuket-departure day trips from around 2,800–3,500 THB. These often use larger boats with 30–40 passengers. Value is reasonable but expect busy sites and less flexibility in the itinerary. The GYG widget below has current availability from both Phuket and Khao Lak. Browse Similan Islands day trips and liveaboards on GetYourGuide.

Top sites by island number

The park’s islands are numbered 1–9 from south to north. Tours typically visit two or three islands depending on departure point and trip length.

Island 4 - Ko Miang (park headquarters)

The administrative centre of the park sits on Ko Miang. There are two beaches here - the main beach with the park office and camping area, and a smaller beach facing east. Snorkeling directly off the main beach is accessible for all levels: leopard sharks rest in shallow sandy areas, and the reef at the southern end holds healthy coral. The ranger station has basic facilities (toilets, a small shop). This is also the only island with overnight accommodation.

Island 8 - Ko Similan (the namesake)

The island the archipelago is named after has the most iconic landmark in the park: Donald Duck Rock, a granite boulder perched dramatically at the water’s edge that does genuinely resemble the cartoon character. The beach on the western side is one of the most photogenic in southern Thailand - wide, white sand backed by the distinctive boulders. Snorkeling around the headlands is excellent, with visibility often over 20 metres. Most day trips include a stop here.

Diving around Island 8 includes Breakfast Bend on the east side, a slope site with abundant fish life, and the deeper Boulder City formations offshore where you can find leopard sharks and occasional reef sharks.

Island 9 - Ko Ba Ngu (Elephant Head Rock)

The northernmost island in most day-trip itineraries is home to Elephant Head Rock - an iconic dive site named for a formation of submerged granite boulders that resembles an elephant’s head from underwater. Depth ranges from 5 to 30+ metres. Currents can be moderate to strong, making it better suited to intermediate and experienced divers. Manta ray sightings are most common here between December and March. Snorkelers can swim around the surface formations, though the better experience at this site is underwater.

Day trip vs overnight

Day trip

The majority of visitors do a single-day return. You depart early (6–7am from Khao Lak, 5–6am from Phuket), visit two to three islands, snorkel or dive for three to four hours total, eat lunch on the boat, and return by late afternoon. It’s enough to see the highlights and is the right choice for most travelers.

Overnight camping on Island 4

The national park operates a campsite on Ko Miang. Tent rental is approximately 150–300 THB per person per night as of 2026; you can also bring your own. Staying overnight means you get the islands in the early morning before day-trip boats arrive - a genuinely significant difference. The sunset and sunrise from Ko Miang’s beach are excellent. Book through the DNP (Department of National Parks) website or via a licensed operator, as the park limits the number of overnight visitors.

Liveaboard (2–5 nights)

For divers wanting depth - literally and figuratively - a liveaboard is the best way to experience the Similans. You sleep on a dive vessel anchored near the islands, log four or more dives per day, and access sites that day-trip boats never reach (northern islands, deeper formations). Cost ranges from approximately 12,000–25,000 THB for a 2–4 night trip. High season (January–March) books out months in advance.

What to bring

• Reef-safe sunscreen - standard chemical sunscreen is prohibited in the national park. Bring a mineral-based (zinc oxide) sunscreen only.
• Cash for the park fee - approximately 500 THB, no card terminals at the pier.
• Underwater camera or housing - visibility is exceptional; a GoPro or similar is well worth it.
• Motion sickness medication - the open-water crossing can be choppy, especially in October–November. Take medication before boarding.
• Light layers - the speedboat ride at 6am is cold even in warm months.
• Snorkel and fins - included in most tours, but your own equipment fits better and makes the experience more comfortable.

Difficulty and accessibility

Snorkeling at the Similan Islands is low difficulty - you enter from the beach or a boat ladder into calm, clear water. Most sites are between 1–5 metres deep for snorkelers. If you can swim confidently, you can snorkel here.

Diving ranges from easy (Island 4’s shallow reef, 5–12m) to demanding (Elephant Head Rock, 20–30m with currents). All dive sites require a verified dive certification. Some sites require advanced certification or prior experience with currents. Confirm the difficulty level of planned dive sites with your operator before booking if you are newly certified.

There are no accessible facilities for wheelchair users on any of the islands. The boat transfer and beach terrain make the trip impractical for those with significant mobility limitations.

Practical notes

• Book tours 2–3 days ahead in peak season (December–February); operators sell out.
• Seasickness: the crossing from Khao Lak is 50–70 minutes on open water; from Phuket, 2.5 hours. Take medication prophylactically.
• Plastic: the park prohibits single-use plastic. Bring a reusable water bottle - many boats now offer filtered water.
• Photography: drones are prohibited throughout the national park.
• Marine life: do not touch coral, stand on reef, or chase marine animals. Ranger patrols are active and fines apply.