Spearfishing in Koh Samui: The Complete Guide

When people think about spearfishing in Thailand, they think Andaman Sea. Similan Islands. Phuket. And yes, the Andaman side has good spearfishing. But the Gulf of Thailand is underrated, and honestly, that is part of why it is good. Less competition. Less pressure on the fish. And dive sites that most spearfishers have never heard of.

I have been spearfishing the Gulf of Thailand from Koh Samui for years. This guide covers everything you need to know if you want to come out here and hunt: the best spots, what species are realistic, the regulations you need to follow, and how to book a trip with us.

Why the Gulf of Thailand

The Andaman Sea gets all the attention because of the Similans and the big pelagics on the west coast. Fair enough. But the Gulf side has a few things going for it that most people overlook.

First, the water is calmer. The Gulf of Thailand is sheltered compared to the Andaman Sea, which means more diveable days per year and less time sitting on the beach waiting for the swell to drop. Second, the fish populations around the Gulf's pinnacles and reefs see far less spearfishing pressure. You are not competing with 15 other boats at every known spot. Third, Koh Samui is a proper base. International flights, real hospitals, good food, reliable logistics. You are not roughing it on a remote island to get in the water.

Best Spearfishing Spots

Sail Rock Area

Sail Rock is the most famous dive site in the Gulf of Thailand, and the surrounding area offers solid spearfishing. The pinnacle itself rises from 40 meters to the surface and attracts schools of trevally, snapper, and barracuda. The reef structure around the main rock creates ambush points where predators patrol. Giant trevally cruise the deeper sections, and yellowtail snapper hold in the mid-water column waiting to be picked off.

You are not spearfishing directly on the main dive site where recreational divers are in the water. The area around Sail Rock, including nearby submerged rocks and ledges, is where you work. There is enough structure in that zone to keep you busy for an entire day.

Samran Pinnacle

Less known than Sail Rock and that is exactly why it is good for spearfishing. Samran Pinnacle is a submerged rock formation south of Koh Phangan that does not get much recreational dive traffic. The fish here are less skittish because they see fewer people. Trevally, snapper, and the occasional Spanish mackerel patrol this site. It is one of my personal favorites because on a good day you can spend hours working the structure without seeing another boat.

Koh Tao Outer Reefs

The outer reefs around Koh Tao, outside the established marine conservation zones, hold good populations of reef fish and pelagics. The drop-offs on the north and west sides of the island attract barracuda and trevally that move between the deeper water and the reef edge. Getting to these spots from Koh Samui takes longer, about 2 hours by boat, so these are full day trips.

Ang Thong Marine Park Edges

Let me be very clear: spearfishing inside Ang Thong Marine Park is illegal. Full stop. Do not do it. But the waters outside the park boundary, where the seabed drops away from the archipelago into deeper Gulf waters, can hold fish. The transition zones between the shallow park waters and the open Gulf attract pelagics. You need to know exactly where the boundary is and stay outside it.

What Species to Expect

I am going to be honest with you about what is realistic. The Gulf of Thailand is not the Coral Sea. You are not going to shoot a 50 kg yellowfin tuna here. But what you can get is solid and varied.

• Giant trevally (GT). The marquee fish in these waters. They patrol the pinnacles and drop-offs. Realistic size range is 5 to 15 kg, with the occasional larger specimen. They are smart, fast, and suspicious. You earn every GT you land.
• Yellowtail snapper. Abundant around reef structures. Great eating fish. You will find them in schools and they are less cautious than trevally, making them a solid target for less experienced spearfishers.
• Barracuda. Common at Sail Rock and the outer reefs. They hang in the water column and give you a clear shot if you can get close enough without spooking them. Not the best eating fish, but a fun hunt.
• Spanish mackerel. Seasonal but present in the Gulf, especially during the calmer months. Fast, strong, and excellent on the grill. When they show up, they are the priority target.
• Grouper. Found in caves and ledges on the reef structures. Ambush predators that sit tight, making them a good target if you can get a clean angle into their holes. Brown-marbled grouper and coral grouper are the most common species here.
• Wahoo. Rare. I am including them because they do pass through the Gulf of Thailand, but I am not going to promise you a wahoo trip. If you land one here, you are lucky and you should buy a lottery ticket on the way home.

Best Season for Spearfishing

March to September is the window. This aligns with the calm season in the Gulf of Thailand when seas are flat, visibility is better, and you can reliably get to offshore sites without battling swells.

Within that window, a few factors matter.

Water clarity. Visibility in the Gulf ranges from 5 to 25 meters depending on conditions. After heavy rain or during plankton blooms, visibility drops and spearfishing becomes difficult. The clearest water typically occurs from April to June. If visibility matters to you, and it should, aim for this period.

Moon phase. Full moon and new moon create stronger tidal currents, which can push baitfish closer to structure and bring predators in to feed. Some of the best spearfishing days happen around the new moon when the water is darker and fish are more aggressive. Full moon days can also be productive but the increased light sometimes makes fish more cautious.

Wind. Northeast monsoon winds from October to January make offshore trips unreliable. You can still spearfish during this period on calm days, but you cannot plan a trip around it. If you are flying to Koh Samui specifically for spearfishing, book between March and September.

Regulations You Need to Know

Spearfishing is legal in Thailand. But there are rules, and you need to follow them.

• Breath-hold only. Spearfishing on scuba is illegal in Thailand. All spearfishing must be done on breath hold. This is not just a Thai regulation, it is the standard in most countries and it is the right way to spearfish.
• No spearfishing in marine parks. Ang Thong Marine Park, Koh Tao marine conservation zones, and any designated marine protected area are completely off limits. The fines are serious and the consequences for the local ecosystem are worse. We do not go anywhere near these areas.
• Respect size limits and protected species. Certain species are protected under Thai fisheries law. Whale sharks, manta rays, and several species of sea turtle are fully protected. Beyond the legal requirements, use common sense. If a fish is undersized, let it grow. If a reef looks heavily fished, move on.
• No night spearfishing. All trips are during daylight hours.

I take regulations seriously. If you book a trip with us, you follow the rules. No exceptions, no "just this once," no looking the other way. The fish will be here next year because we choose to fish responsibly this year.

What We Offer

We run full day spearfishing trips from Koh Samui. Here is what that looks like.

• Private boat with captain. A dedicated longtail or speedboat depending on the destination. The captain knows these waters and the sites.
• All equipment provided. Spearguns, freediving fins, masks, weight belts, catch bags, and a cooler with ice for your fish. You do not need to bring any gear.
• Diego guides personally. I am in the water with you. This is not a "drop you at the site and wait on the boat" operation. I know where the fish hold, I know the terrain, and I can coach you on approach technique if you are less experienced.
• Maximum 4 spearfishers per trip. More than 4 people in the water gets chaotic and dangerous. Four is the cap. If your group is larger, we run two boats.

Pricing: 24,000 to 35,000 THB per boat depending on the destination and boat type. Closer sites like Samran Pinnacle are at the lower end. Full day trips to the Sail Rock area or Koh Tao outer reefs are at the higher end due to fuel costs. The price covers the entire boat, so split it between your group.

Check the spearfishing page for full details and current availability.

What to Bring

We provide all the spearfishing equipment. You just need to show up with the basics.

• Reef-safe sunscreen (you will be in the sun all day)
• Hat and sunglasses for the boat
• Plenty of water (minimum 2 liters per person)
• Snacks or lunch for the boat
• GoPro or waterproof camera if you want footage
• Towel and dry clothes for the ride back

If you have your own speargun and fins that you prefer, bring them. But you do not need to. The equipment we provide is well maintained and suitable for the conditions here.

Who This Is For

Two types of people book these trips.

Experienced spearfishers who have hunted in the Mediterranean, Australia, Hawaii, or wherever, and want to explore new waters. You know how to dive, you know how to shoot, and you just need someone who knows the local spots and can put you on fish. That is what I do. You will spend the day hunting, not learning basics.

Beginners who want to try spearfishing under proper guidance. If you have done some freediving and want to take the next step, a guided spearfishing trip is the way to start. I will teach you how to approach fish, where to aim, how to handle a loaded speargun safely underwater, and all the breath-hold techniques that make spearfishing effective. You do not need to be an expert freediver, but you should be comfortable in open water and able to dive to at least 5 to 10 meters on a breath hold.

If you have never been in the ocean before, start with a freediving course first. Get comfortable underwater, learn to equalize, and then come back for spearfishing. The skills transfer directly.

Book a Spearfishing Trip

Check the spearfishing page for full trip details, or message me directly on WhatsApp to check availability. Tell me your dates, group size, and experience level, and I will put together the right trip for you.

The Gulf of Thailand has fish. The water is warm. The competition is minimal. Come hunt.