There are places in Southeast Asia where the fishing still feels genuinely wild — where you can work a popper over a coral bombora at dawn and wonder honestly whether anything has thrown a lure at that exact piece of water before you. The Mergui Archipelago is one of those places, and it may be the last of its kind within reach of an angler based in Thailand.
Stretching along the southern coast of Myanmar (Burma) from roughly the latitude of Ranong down toward the Malay Peninsula, Mergui comprises more than 800 islands scattered across some 36,000 square kilometres of Andaman Sea. The interior passages are a maze of limestone karst, mangrove creek, and open channel that would take a lifetime to fully explore. Most of it has never seen a fishing rod.
Getting There: Ranong and the Liveaboard Corridor
The practical gateway is Ranong, Thailand's smallest and wettest province, sitting at the northern end of the Andaman coast. From Ranong's port, liveaboard vessels cross into Myanmar waters after clearing formalities at Kawthaung, the small border town on the Myanmar side. The crossing is straightforward but mandatory — there is no skipping the paperwork.
Foreign-zone permit fees apply to all non-Myanmar nationals fishing these waters. Your operator handles the filing, but the costs are real and vary by season and vessel type. Budget accordingly when comparing trip prices with other Andaman destinations. The permits exist because Myanmar has — slowly, imperfectly — begun treating the archipelago as a managed resource rather than an open commons. For anglers, that structure is worth supporting.
Most trips run five to ten days. Anything shorter barely justifies the transit. The most productive itineraries combine time on the outer seamounts (the Burma Banks) with exploration of inner island passages and reef edges closer to shore.
Liveaboard itineraries that include both the Burma Banks and inner Mergui island passages give you the widest species coverage. Check our liveaboard operators Thailand overview for vessels that hold Myanmar permits.
The Species: What Lives Out There
The Mergui fishery divides roughly into two environments — open blue water and hard structure — and each produces a different cast of species.
Giant Trevally and the Reef Edges
Giant trevally are the headline act at Mergui, and for good reason. The reef edges and rocky headlands of the inner archipelago hold resident GT populations that rarely encounter surface lures. Fish over ten kilograms are routine. Twenty-kilogram fish are caught regularly. The occasional 30-plus-kilogram specimen reminds you that this water has been resting undisturbed for most of the past century.
Surface popping is the method of choice. You work large stickbaits and poppers across the wash at the base of rocks, along current lines beside points, or over shallow bomboras as the tide floods. The takes can be sudden and violent. GTs at Mergui have not learned caution.
Jigging the deeper reef structure — particularly around the Burma Banks seamounts — produces another class of fish: dogtooth tuna, coral grouper, brown marbled grouper, red snapper, and golden snapper. These fish sit in ambush along ledges and drop-offs in 30 to 80 metres of water. Slow-pitch jigging with metal jigs in the 150–300g range is increasingly the technique of choice; vertical jigging with heavier butterfly-style jigs also works well. See our jigging guide for Thailand deep water for setup details.
Dogtooth Tuna: The Deepwater Prize
Dogtooth tuna deserve a paragraph of their own. They are among the most powerful fish in the ocean relative to their size, with a habit of diving straight for structure the instant they feel the hook. A dogtooth on a jig at 50 metres, with 30 metres of rock below it, is a genuine test of tackle and nerve. The Burma Banks, with their seamount topography and strong tidal currents, concentrate dogtooth tuna reliably. Fish from 15 to 40 kilograms are caught across the season. Larger specimens are documented but rare.
Pelagics: Sailfish and Marlin
The open water around the outer islands and along the western edge of the archipelago holds sailfish through the early part of the season (November to January) and scattered marlin throughout. Neither species is as consistently reliable here as at dedicated pelagic destinations — Mergui is not primarily a billfish fishery — but liveaboards trolling between islands or running to the Banks routinely raise both. If your primary goal is billfish, the Andaman deep canyons or Koh Rok area may suit you better.
Season and Conditions
The northeast monsoon — roughly November through April — defines the fishing window. December, January, and February are the calmest months, with light winds and manageable swell in the outer passages. March and April bring gradually building seas and occasional early southwest-monsoon squalls, but experienced operators continue running trips into late April.
The southwest monsoon (May through October) renders the outer Banks inaccessible by all but the sturdiest vessels, and most operators suspend Myanmar-permit operations entirely. Inner passages can remain fishable in moderate conditions, but the trip product changes significantly.
Water temperatures hold between 27°C and 30°C through the prime season. Visibility at the Banks can reach 30 metres or more in calm conditions; inner reefs and channel edges are often more turbid, depending on tidal state and recent rainfall.
A dogtooth tuna on a jig at 50 metres, with 30 metres of rock below it, is a genuine test of tackle and nerve.
Tackle for Mergui
The range of techniques used at Mergui means you will want multiple outfits if space allows.
GT popping: PE 6–8 braided line, 80–100lb fluorocarbon leader, heavy topwater or stick popper rods rated 80–180g. Reels with strong drags and at least 300m of braid capacity. This is no place for undersized gear — see the full GT popping tackle guide.
Jigging: PE 3–5 for slow-pitch, PE 4–6 for vertical jigging. Rods suited to the technique — slow-pitch rods in 150–250g rating, or conventional jigging rods for deeper water. Jigs from 150g to 400g. Assists with heavy hooks.
Light-tackle inshore: A 20–30lb spinning outfit for snapper, queenfish, and reef species in the inner passages is worth packing. Some of the most enjoyable sessions at Mergui happen on lighter gear in protected anchorages at dusk.
Trolling: If your vessel trolls between fishing spots, a pair of 50–80lb outfits rigged with skirted lures covers the sailfish and wahoo risk without taking up much deck space.
Operator Considerations
There are no day-trip options at Mergui. The logistics — Myanmar permits, fuel loads, and the sheer distance from any port — make liveaboard the only viable format. This shapes the market: you are choosing between specialist fishing liveaboards (typically converted Thai fishing vessels or purpose-built aluminum or steel hulls) and dive liveaboards that accommodate fishing as a secondary activity.
The distinction matters. Specialist fishing vessels carry proper rod holders, fighting chairs or harnesses for heavy jigging, and crew familiar with big-game technique. Dive liveaboards may be more comfortable but less adapted to serious fishing. Ask specifically about onboard fishing infrastructure before booking.
Permit costs, vessel type, and itinerary focus vary significantly across operators. Our liveaboard operators Thailand page lists current providers with Myanmar licences.
Conservation Notes
Mergui's relative isolation has preserved fish populations that elsewhere in Southeast Asia have been severely depleted. That abundance is fragile. Responsible anglers should discuss catch-and-release policy with their operator before departure — particularly for large GT, dogtooth tuna, and grouper, which are the most ecologically significant species in the system. Many operators already enforce release for trophy fish; some allow limited table fish of smaller snapper and grouper.
Avoid operators who encourage or permit the killing of sharks. Reef sharks — whitetip, blacktip, and grey reef — are present throughout the archipelago and are a sign of ecosystem health. Review Thailand's protected and endangered species rules for current status on species you might encounter.
The Mergui Archipelago is one of Asia's last unfished frontiers. It will stay that way only if the anglers who visit treat it with the care it deserves.
Planning Your Trip
For most anglers based in Thailand, the logistics run through Ranong: fly Bangkok–Ranong (60 minutes), spend a night in town, and board your vessel the following morning. Some operators arrange transfers from Phuket or Khao Lak for groups that prefer a longer overland leg.
Budget five days minimum for a meaningful Mergui experience. Seven to ten days allows proper coverage of both the Banks and inner archipelago. See our 7-day Andaman fishing itinerary for a template that includes Mergui as a northern component.
The best time to fish in Thailand guide covers seasonal windows across all Andaman destinations if you are planning a broader trip around a Mergui liveaboard.
