Thailand protects more than 150 national parks, and the gap between the famous few and the rest is wide. The parks below are the ones worth building a trip around — for rainforest old enough to predate the Amazon, waterfalls you can actually swim in, limestone islands that turn up in films, and the country’s highest mountain. Fees for foreigners run higher than the Thai price, but they are modest, and almost every park rewards an early start before the tour vans arrive.
Khao Sok National Park
Khao Sok in Surat Thani protects one of the oldest evergreen rainforests on earth, and its centrepiece is Cheow Lan Lake — a reservoir ringed by limestone cliffs where you sleep in floating raft houses and wake to gibbon calls. Day trips run from the pier, but a night on the water is the reason to come. The dry months (December to April) give the calmest lake and clearest trails; the wet season turns the jungle louder and greener but floods some paths. Foreigner entry is 300 THB, and most visitors base themselves in the village outside the main entrance.
Doi Inthanon National Park
Doi Inthanon, an hour and a half south-west of Chiang Mai, holds the highest point in Thailand at 2,565 metres. The summit sits in cool cloud forest draped in moss, and the twin royal pagodas of Naphamethinidon and Naphaphonphumisiri stand just below it with manicured gardens and long valley views. Wachirathan is the park’s most powerful roadside waterfall. Bring a layer — the top can drop near freezing on winter mornings, the one place in Thailand where that sentence is literal. Entry is 300 THB.
Erawan National Park
Erawan, in Kanchanaburi, is built around a seven-tier waterfall of emerald pools that step up through the forest, and unlike most Thai falls you are allowed to swim in them. Small fish nibble at your feet in the lower pools; the upper tiers thin out the crowds because the climb deters day-trippers. Go on a weekday and arrive early, because by late morning the lower pools fill with families. The falls run year-round but are fullest from July onward. Entry is 300 THB.
Khao Yai National Park
Khao Yai was Thailand’s first national park and is now part of a UNESCO World Heritage forest complex three hours from Bangkok. It is the country’s most reliable place to see wildlife in the open — wild elephants cross the roads at dusk, gibbons and hornbills work the canopy, and the Haew Narok and Haew Suwat waterfalls (the latter featured in the film The Beach) anchor the trails. A car or tour helps, as the park is large and public transport stops at the gate. Foreigner entry is 400 THB.
Similan Islands National Park
The Similans, eleven granite islands off Phang Nga, are Thailand’s headline dive and snorkel destination — visibility runs to 30 metres over coral and granite boulder swim-throughs. The catch is access: the park closes from mid-May to mid-October for the monsoon and reopens on 15 October, and overnight stays are tightly limited, so most people visit on speedboat day trips from Khao Lak or Phuket. Marine-park entry is around 500 THB. Book early in the season before the reefs see their heaviest traffic.
Mu Ko Ang Thong National Park
Ang Thong is a scatter of 42 limestone islands in the Gulf, reached on day trips from Koh Samui or Koh Phangan. The set-piece is Emerald Lake (Talay Nai), a hidden saltwater lagoon ringed by cliffs that you reach by a short steep climb — the view from the ridge above it is the image that supposedly inspired the novel The Beach. Kayaking, snorkelling and viewpoint hikes fill a day. The park can close in rough Gulf weather around October to December.
Ao Phang Nga National Park
Ao Phang Nga is the bay of vertical limestone karsts north-east of Phuket, best known for Khao Phing Kan — “James Bond Island” from The Man with the Golden Gun. The honest way to see it is by sea kayak through the tidal sea caves and mangrove channels rather than fighting the crowds at the famous rock itself. Tours leave from Phuket and Krabi. The water is calmest in the dry season, and the mangroves are worth the trip even when the headline island is busy.
Khao Sam Roi Yot National Park
Khao Sam Roi Yot — “the mountain of three hundred peaks” — sits on the coast near Hua Hin and pairs limestone hills with freshwater marshes that draw migratory birds in the cool season. Its standout is Phraya Nakhon Cave, where a royal pavilion stands under a collapsed cavern roof and, for about an hour mid-morning, a shaft of sunlight lands directly on it. The walk in is short but steep. It makes an easy day trip from Hua Hin or Pranburi.
Doi Suthep–Pui National Park
The forested range on Chiang Mai’s western edge holds the city’s most-visited temple, Wat Phra That Doi Suthep, along with the Bhubing royal gardens and the higher summit of Doi Pui. You can fold a temple visit, a hill-tribe village and a couple of short trails into half a day, all within a 30-minute drive of the old city. Mornings are clearest; the burning season (roughly February to April) can leave the views hazy.
Kaeng Krachan National Park
Kaeng Krachan, inland from Phetchaburi and Hua Hin, is Thailand’s largest national park and another UNESCO-listed forest, known among naturalists for its birdlife and its early-morning sea of mist seen from the Phanoen Thung viewpoint. Access is more restricted than the headline parks — sections require permits and the upper road runs on a one-way timed system — but that is exactly why the wildlife holds. The Pala-U waterfall on its eastern edge is an easy add-on from Hua Hin.
Frequently Asked Questions
What is the entrance fee for national parks in Thailand?
Foreigners pay more than Thais. Most land parks charge 200–400 THB for adults (Khao Sok and Doi Inthanon 300 THB, Khao Yai 400 THB), and marine parks such as Similan and Ang Thong charge around 300–500 THB. Children pay roughly half. Tickets usually cover 24 hours.
When is the best time to visit Thailand's national parks?
The cool, dry season from November to February is the most comfortable across the country. Waterfalls are fullest during and just after the wet season (roughly July to November), while marine parks like the Similans only open from mid-October to mid-May.
Which national park is best for first-time visitors?
Khao Yai is the easiest to reach from Bangkok and gives you a strong chance of seeing wild elephants and gibbons. Khao Sok suits anyone wanting rainforest and a night in a floating raft house on Cheow Lan Lake.
Can you stay overnight inside the parks?
Yes. Most parks run basic bungalows and campsites bookable through the Department of National Parks, and Khao Sok has private floating raft-house resorts on the lake. Book ahead for weekends and holidays.
Are the Similan Islands open all year?
No. Mu Ko Similan National Park closes from around 15 May to 15 October each year to let the reefs recover and because monsoon seas make the crossing dangerous. It reopens on 15 October.
