Thailand Saltwater — The Two-Sea Context
Thailand's saltwater fishing splits between two distinct marine environments with different oceanographic characters, different species, different seasons, and — critically — different optimal fishing windows. The Andaman Sea on the western coast is a deep-water, high-visibility, pelagic fishery dominated by the northeast monsoon season (November to April), which brings calm seas, concentrated baitfish, and active sailfish, GT, and tuna populations. The Gulf of Thailand on the eastern coast is a shallower, warmer body of water with a year-round inshore fishery that follows the opposite monsoon pattern.
This list focuses exclusively on the Andaman side — where Thailand's most celebrated saltwater fishing is concentrated — and on the one Andaman-adjacent destination (the Mergui Archipelago) that technically falls within Myanmar's waters but is accessible only through Thailand. The Gulf coast's best experiences are covered in the charter directory and in dedicated regional articles.
Liveaboard versus day-charter
The first distinction in Andaman saltwater planning is whether to day-charter or liveaboard. Day-charter fishing from Phuket, Khao Lak, or Krabi accesses the reefs within a 30-nautical-mile radius of port. Liveaboard fishing accesses the outer Similans, the Surin Islands, and the frontier Mergui Archipelago — destinations unreachable on a day-charter budget or transit time. The liveaboard experience costs more per day but covers water that changes the character of the entire trip.
1 — Similan/Surin Liveaboard Circuit
The Similan Islands — nine islands and associated reefs approximately 70 km northwest of Khao Lak — form the heart of Thailand's best-protected marine park. The Surin Islands, 60 km north of the Similans near the Myanmar border, hold reefs of similar quality. Together, the Similan-Surin circuit is the gold standard for Andaman liveaboard fishing in Thai sovereign waters.
The reef quality at the Similans is the defining feature. The national park status has limited the commercial fishing pressure that has degraded the reefs south of Phuket, and the result is fish populations — GT, grouper, snapper, napoleon wrasse, coral trout — in condition and numbers that day-charter reefs cannot replicate. The GT in particular at key pinnacles like West of Eden, Elephant Head Rock, and Beacon Point are larger and more numerous than those encountered on the mainland-adjacent inshore reefs.
What a Similan fishing liveaboard delivers:
- GT popping at dawn on outer reef walls and pinnacle structures
- Jigging for dog-tooth tuna at 60–100 metres on deeper structure
- Trolling passes for Spanish mackerel and wahoo between reef stops
- Night fishing over reef structure for snapper and grouper
- Snorkelling and diving at stops between fishing sessions (for anglers who want the full experience)
Liveaboard operators: Several Khao Lak-based operators run dedicated fishing liveaboards to the Similans and Surin. Vessel quality varies — from basic converted dive boats with rods to purpose-configured fishing vessels with proper rod holders, tackle rooms, and fish-cleaning stations. Research the operator's track record with fishing-specific trips rather than the dive-trip record.
Season: October 15 to May 15 (Similan National Park opening dates). Book at least two months ahead in the December–February peak.
Cost: USD $300–600 per person per night depending on vessel quality and programme.
2 — Phuket Dawn Sailfish at Tap Lamu
Tap Lamu harbour — south of Khao Lak and north of Phuket — is the departure point for several of the most experienced Phuket sailfish charter operations. The location's significance is twofold: it reduces the transit time to the FAD grounds (the offshore fish-aggregating device system at 15–35 nautical miles) compared to Chalong, and it places the boat on the southern edge of the Andaman current system that concentrates sailfish during the November–March peak.
The Phuket-area sailfish fishery — Tap Lamu and the Chalong/Boat Lagoon departures combined — is one of the highest-volume Indo-Pacific sailfish destinations in the world. During January and February, on days when the FADs are working and the current is aligned, a single boat can encounter and fight twenty or more sailfish in an eight-hour session. These are not small fish: 30–50 kg is typical, with exceptional specimens reaching 60+ kg.
The technique: Traditional live-bait trolling dominates the Phuket sailfish fleet. A spread of live scad or small mackerel trolled across the FAD zone, with outriggers spreading the lure coverage, intercepts feeding fish as they rise to the surface. The bite — when a sailfish takes a live bait — is a rapid run followed by a jump that confirms the species. On productive days, multiple simultaneous hook-ups are common and the boat becomes a rotating fighting chair.
The ethical dimension: Nearly all reputable Phuket sailfish operators practice 100% catch-and-release on sailfish. The fish is fought, photographed, documented if required for record purposes, and released alongside the boat with a brief reviving period in the water. The welfare protocols at the better operators — no gaff, no prolonged out-of-water handling, immediate water-side release — are genuinely good.
Where to book: Chalong pier, Boat Lagoon, Phuket Yacht Haven, and Tap Lamu harbour all have dedicated sailfish operators. See our Phuket charter overview for current operators.
3 — Mergui Archipelago (Myanmar)
The Mergui Archipelago is what the Andaman used to be before thirty years of recreational fishing pressure transformed the reefs south of Phuket from frontier wilderness to managed fishery. Eight hundred islands in Myanmar's Tanintharyi Region, the Mergui has been accessible to visiting anglers since the mid-2000s via the border crossing at Ranong/Kawthaung, and the operators who have built their businesses around the archipelago describe it consistently in the same terms: fish that have never seen a surface popper. Reefs that have never been jigged. GT in sizes that suggest generations of undisturbed feeding.
The fishing quality at the Mergui is genuine. Documented catches from established liveaboard operators include GT exceeding 40 kg on surface lures, dog-tooth tuna in the 30+ kg range, and grouper of species and sizes that do not exist on the pressured Thai Andaman reefs to the south. The frontier status is real: access to these reefs requires multi-day liveaboard commitment, Myanmar permits obtained in advance, and acceptance of the infrastructure limitations of a genuinely remote destination.
Access: Liveaboard vessels depart from Ranong (15-hour journey north from Phuket, or fly Bangkok–Ranong). Myanmar permits processed by the operator — budget 6–8 weeks for permit applications. Operators: MV Halcyon (one of the most established), Myanmar Andaman.
Season: November through April. The Mergui itinerary is typically 7–12 days including transit time.
Cost: USD $400–700 per person per night depending on vessel and itinerary. A 10-day Mergui trip is a significant investment.
4 — Andaman Deep Canyons: Koh Racha Yai and Racha Noi
The Racha Islands — Koh Racha Yai (the larger, tourist-oriented island) and Koh Racha Noi (the uninhabited, steeper-profiled island further south) — sit approximately 25 km south of Chalong and represent the most accessible deep-structure GT and dog-tooth tuna fishing from the Phuket port system. Racha Noi in particular has underwater topography that concentrates large fish: steep walls dropping from 10 metres to 50+ metres, strong current channels between the northern and southern reef sections, and submerged pinnacles that aggregate pelagics in feeding position.
The GT popping at Racha Noi is the most accessible version of this type of fishing from Phuket — no overnight transit, no liveaboard commitment, reachable on a day-charter departure from Chalong in 45 minutes. The fish are smaller than Mergui specimens — 10–25 kg is typical at Racha — but the density of fish on the better structure ensures that a popping session with multiple hook-ups is achievable in a standard day.
Dog-tooth tuna are the deeper-jig target. At 60–100 metres over the canyon structure north and east of Racha Noi, slow-pitch jigging produces dog-tooth in the 10–30 kg range with a fight character unlike any other tuna species — a broad-shouldered, close-to-the-structure battle that keeps the angler working throughout.
Where to book: Any Phuket charter that specifically lists Racha Noi jigging and popping. Not all Phuket charters reach Racha — confirm the specific grounds with the operator before booking. Expect a full-day private charter for this programme.
5 — Phang Nga Bay Inshore Mangrove
Phang Nga Bay — the enormous estuary system north of Phuket, bounded by limestone karst on three sides and draining the Phang Nga River and its tributaries into the Andaman — is the most dramatically different fishing environment from any other Andaman destination. Where the Similans, Racha, and Mergui are blue-water, high-energy, pelagic fisheries, Phang Nga Bay is green water: tidal channels through mangrove, shallow gravel flats, narrow cave passages through limestone, and a fish fauna that includes no sailfish, no GT, and no tuna — but does include species and environments unavailable anywhere else.
The mangrove environment holds:
- Mangrove snapper (Lutjanus argentimaculatus) — aggressive, red-flanked, taking small jigs and shrimp in the channel shade
- Barramundi in the tidal creek mouths — wild animals in brackish conditions, responsive to surface lures and live bait at dawn
- Archerfish (Toxotes jaculatrix) — one of the world's most biologically remarkable fish, targetable on micro lures along the mangrove fringe
- Queenfish (Scomberoides commersonnianus) — in packs along the mangrove edge on the bay side
- Small GT on the outer bay rocky structures — not the 30 kg fish of the offshore reefs, but aggressive and plentiful
The visual experience of Phang Nga Bay fishing — navigating a longtail through passages between vertical limestone pillars, casting into cave openings at low tide, watching archerfish spit at insects from the mangrove fringe — is unlike anything else in Thailand's coastal fishing.
Access: Day trips from Phang Nga town pier, from Ao Por pier on Phuket's east coast, or from Koh Yao Noi island. Several longtail operators specifically offer mangrove fishing programmes for international visitors; these are generally arranged through guesthouses on Koh Yao Noi or through specialist fishing tour operators operating out of Phang Nga town.
Season: Year-round, but the calmest and clearest conditions are November through April. Monsoon-season fishing in Phang Nga Bay continues because the bay's protected position limits wave height — the mangrove channels are fishable on most days regardless of open-sea conditions.
The two-destination combination
The most complete Andaman saltwater fishing trip combines offshore liveaboard fishing (Similans or Mergui) with a Phang Nga Bay inshore day. The contrast between the two environments — blue water and big pelagics versus green mangrove and estuary species — is as complete a cross-section of Thai saltwater fishing as a single trip can deliver.
