Drones, Divers and Recycling Drive Koh Phangan's Marine Recovery

More than three tonnes pulled from the Gulf

More than three tonnes of marine waste have been removed from the Gulf of Thailand in the four months leading up to November 4, 2025, by the Aerial Recon and Recovery Initiative and its volunteers. On Koh Phangan, the group combines drones, artificial intelligence and models of ocean currents to find abandoned fishing gear, then sends trained crews to recover it when conditions are safe.

Scientist Tania Kanchanarak returned to her birthplace after years of drifting plastic and lost fishing equipment damaged the waters around an island better known for its bright beaches and relaxed pace of life. She co-founded the initiative, known locally as ARRI, to tackle debris that scars coral reefs and traps marine animals.

ARRI's volunteers include many young islanders. Their work gives people whose livelihoods depend on tourism and fishing a direct role in protecting the sea, while technology helps narrow the search for hazardous nets and other waste.

After months of trial runs and adjustments to its computer model, ARRI reports accurate mapping of debris fields. Its team scans the sea surface from above, identifies likely waste in near real time and uses the resulting maps to plan retrieval dives. Finding a target before sending divers into the water reduces wasted effort and helps crews prepare for the risks.

Koh Phangan's cleanup is connected to a wider effort across Thailand's gulf islands. Koh Tao and Koh Samui are developing coral nurseries, artificial reefs and programs in which residents and visitors collect scientific observations. Government agencies and private partners are also testing large engineered reefs and closer cooperation with coastal communities. The projects connect waste removal, reef repair and local employment, with different teams handling different parts of the task.

How drones turn a search into a recovery plan

ARRI's drones fly low and slowly over planned grids, photographing the sea with cameras that capture detailed images. The team looks for surface patterns and shadows just below the water that could reveal nets, fishing lines or rafts of plastic.

On shore, an artificial intelligence model trained on thousands of labeled images marks likely debris. In this setting, AI is a classification tool: it learns visual patterns and sorts images according to what they appear to contain. Shape, edges and color contrast help it separate possible waste from seaweed, waves and marine life.

The model can review images faster than a person and does not tire. Field checks remain part of the process. Team members inspect selected locations, correct labels when needed and put those corrections back into the training material. That repeated cycle helps the model adjust to changes in light and water conditions.

Wind and current simulations then estimate where the debris may drift. Tides and seasonal monsoon patterns influence those movements in the Gulf of Thailand, so a position recorded during a drone flight becomes the starting point for planning where crews should search next.

Once the team verifies a hotspot, trained divers and boat crews arrange a retrieval mission. Divers carefully cut nets away from coral heads, bundle sections of rope and lift them to boats in stages. The staged lifting helps avoid sudden surges that could damage the reef.

Safety planning considers water movement, visibility and the possibility of a diver becoming tangled. Recovered waste is sorted on land for recycling or repurposing. Each removal is recorded, allowing ARRI to identify places where debris repeatedly gathers and refine its current models for future patrols.

Why lost fishing gear needs a quick response

Ghost gear is the name given to nets, lines and traps that are lost or discarded at sea. It can drift for years, entangling fish, sea turtles and dolphins long after anyone has stopped using it for fishing.

Nets can also smother coral and break fragile reef structures. As their fibers deteriorate, they shed microplastics, tiny plastic particles that enter the food web. Around Koh Phangan, the damage reaches beyond wildlife because healthy reefs and clean water are part of the attraction that supports tourism businesses.

ARRI and its partners prioritize ghost gear because one abandoned net can cause repeated harm as it moves. Retrieving it quickly reduces that direct pressure on marine animals and on reefs already affected by warmer seas and coastal development.

A collaboration lasting six months with seafood producer Thai Union Group covers a survey zone of 12 square kilometers around Koh Phangan. The campaign aims to remove more than 3.2 tonnes of debris, sort the material, recycle what can be used and return it to productive use through a circular economy. That means keeping materials in use instead of treating them as waste after one purpose.

The more than three tonnes removed in the preceding four months is a reported result; the more than 3.2 tonnes is the target for the campaign lasting six months. The partnership's exact start and end dates have not been given. Mapping helps crews choose efficient routes and retrieve nets before they drift into deeper water or more delicate habitats.

Funding the work at sea and on shore

Thai Union Group's support has helped ARRI expand its work through equipment, boat time and local hiring. The partnership also connects recovery operations to recycling trials, aiming to keep collected waste in the value chain instead of sending it to landfill.

The sponsor describes the project as a practical approach to tackling marine pollution at its source while creating local jobs in surveying, safe retrieval and materials processing. Those tasks link the search at sea to the work needed after a boat returns with a load of nets.

Across Thailand, conservation groups often operate with a combination of government oversight, tourism revenue and corporate funding. That mix helps small teams test tools such as AI mapping while continuing the physical work of removing debris.

Technical knowledge alone is only one part of the operation. Boat access, trained crews and community trust help make the work possible in places where fishing, tourism and conservation share the same waters.

Koh Samui turns recovered nets into bricks

On Koh Samui, a volunteer network called E2C works with ARRI to give debris that cannot be recycled through its existing routes another use in construction. Engineers and builders have shown that chopped net fibers mixed into concrete can increase tensile strength and flexibility.

Tensile strength describes how well a material withstands being pulled apart. Greater flexibility allows it to tolerate some movement before cracking. The resulting tougher bricks are particularly useful in coastal settings, where salt and humidity put building materials under stress.

The team produces about 100 bricks a day and has used more than 720 kilograms of recovered nets and plastic so far. The process connects removal from the sea with a product that can serve the community on land.

Students and residents learn from the molds and the production process. Schools and local shops display the bricks and explain how they are made to visitors, showing how recovered waste can become a resource.

E2C's work follows a straightforward sequence: remove the nets, keep the plastic out of the landfill stream and turn it into something useful. Its partnership with ARRI gives material brought ashore a destination beyond storage or disposal.

Krabi builds a collection system around households

In Krabi, the Second Life initiative led by Wongpanit Krabi Co Ltd focuses on the collection and processing network that waste recovery needs. The program works with more than 20,000 families, teaches households to sort their waste and establishes reliable collection.

Plastic with little resale value is routed to facilities that can process it. This reduces the need to ship waste to Bangkok, lowers disposal costs and helps keep plastic out of waterways from which it could drift toward sensitive reefs.

The system has certification under an international standard identified as VERA. Alongside collecting existing waste, Second Life promotes prevention, including reducing materials such as PVC that do not decompose.

Household sorting and changes by businesses reduce the amount of waste that may eventually reach the sea. Krabi's approach therefore addresses an earlier stage of the problem than a retrieval dive: the point at which materials are used, separated and collected on land.

Seven retired platform jackets become reef structures

Near Koh Phangan, the Department of Marine and Coastal Resources and its partners completed Thailand's first project converting retired offshore platform structures into artificial reefs in 2020. Seven platform jackets, the steel support frames beneath offshore installations, were relocated to a protected site.

The frames were placed at depths of about 38 to 40 meters, with at least 15 meters of water above them for navigation safety. The designated artificial reef area covers four square kilometers, while the jackets occupy a much smaller footprint within it.

The steel structures provide height above the seabed and hard surfaces where corals and other invertebrates can settle. Early studies of jacket structures in the Gulf of Thailand suggest they can support diverse fish communities and draw divers toward deep water sites, easing pressure on natural reefs.

Agencies continue to monitor the site to understand how currents, sediment and interactions among species affect growth. The work links construction of an underwater habitat with observation of how that habitat develops over time.

The developments described across the islands span several periods:

• 2020: Seven retired platform jackets were installed at a protected artificial reef site near Koh Phangan.
• The four months leading up to November 4, 2025: ARRI and volunteers removed more than three tonnes of marine waste from the Gulf of Thailand.
• As of November 4, 2025: ARRI's collaboration with Thai Union Group covers a campaign lasting six months, surveying 12 square kilometers and targeting removal of more than 3.2 tonnes.

Reef repair depends on conditions in the water

Divers across the Gulf of Thailand carry out underwater cleanups, remove invasive algae that grow over stressed coral and stabilize broken reef structures. These activities complement ghost gear removal by addressing other pressures on damaged reef sites.

When storms break branching corals, conservation teams can use fragments of opportunity, small pieces that can be grown in nurseries and later replanted. These measures can speed recovery when temperature and water quality are within safe ranges, although they are not a cure for every problem affecting a reef.

Research on restoration shows both promise and limits. Coral microfragmentation, nursery growth and mineral accretion can increase local coral cover. Microfragmentation uses small coral pieces for regrowth, while nurseries provide places to grow coral before it is moved to a restoration site.

Heat stress, sedimentation and poor water quality can overwhelm even carefully designed projects. Artificial reefs serve as an additional tool alongside protection of natural habitats. Many Thai programs therefore combine structures, careful transplantation and water quality measures with enforcement of protected zones.

Koh Tao connects diving, science and conservation funding

Koh Tao, north of Koh Phangan, has developed conservation programs through its dive schools. Visitors learn to survey reefs, remove debris and help restore coral. Conservation certifications among divers are rising as bleaching events expand worldwide.

Citizen scientists identify coral types, record color changes that signal stress and log fish populations that respond to reef health. Citizen science means people who are not professional researchers help collect observations. Their records feed into global projects and inform local management.

Local groups also maintain artificial reef sites, care for coral nurseries and organize regular cleanups. One method used on Koh Tao is mineral accretion, which sends a current at low voltage through steel frames underwater.

The current encourages minerals in seawater to crystallize on the steel, creating a surface where coral fragments can attach and grow. Results vary with the location and conditions, although some sites show faster early growth, especially for branching coral species commonly used in restoration.

Koh Tao has introduced a tourist user charge of 20 baht per visitor, with legal backing to direct funds toward waste management, conservation and public services. The charge connects visitor revenue to the services and environmental work needed by the island.

Community groups and businesses promote sunscreen described as reef safe and support rules limiting boat traffic over shallow coral. Recycling ventures turn plastic waste into useful products, helping keep beaches and dive sites clean during busy seasons. Clear rules and revenue devoted to shared needs give tourism a role in supporting conservation.

AI helps teams read reef images faster

Artificial intelligence is also being used to study reef condition beyond ARRI's search for floating debris. A recent study trained deep learning models on more than 20,000 underwater images from the Indo Pacific, teaching them to classify signs of disease, predation, competition and rubble.

An ensemble of advanced model architectures performed better than individual models and reached a strong micro F1 score. An ensemble combines several models, while the micro F1 score measures classification performance by balancing successful detections against missed or incorrect labels across the dataset.

Automated classification helps researchers work through large image backlogs and track changes more consistently than manual review alone. For conservation teams with limited time, faster processing makes observations easier to turn into decisions about where to concentrate fieldwork.

Across the islands, the technology has several uses. ARRI identifies likely ghost gear in drone images. Citizen scientists help train algorithms to recognize fish in survey videos, reducing the hours biologists need to spend reviewing footage.

Managers can use those records to direct divers toward threatened sites or identify areas where recovery and protection are working. Field skills remain central: volunteers still have to check model output, handle boats and complete recovery missions safely.

Visitors, residents and fishers have practical roles

Visitors can choose dive operators that contribute to reef monitoring and debris removal. Following guidance on buoyancy and fin movements helps prevent accidental contact with coral. Visitors can also use sunscreen described as reef safe, respect zones where boats are prohibited and follow temporary closures intended to give stressed reefs time to recover.

Avoiding fish feeding and carrying a refillable bottle and reusable bag are other steps described by the island conservation effort. Keeping plastic out of the water reduces the amount that crews may later have to search for and retrieve.

Residents and businesses can improve sorting at the source, support local recycling partners and join monthly cleanups. Fishers can report lost nets and mark their locations for retrieval crews, giving search teams a practical starting point.

Schools can teach students how reefs support coastal protection and food security. Across the gulf islands, these actions connect households, fishing crews, tourism businesses, recyclers and conservation teams to the same task: reducing waste and giving damaged marine habitats better conditions for recovery.

What to Know

• ARRI, co-founded by scientist Tania Kanchanarak, uses drones, AI and current models to locate debris around Koh Phangan and plan retrieval dives.
• ARRI and volunteers removed more than three tonnes of marine waste from the Gulf of Thailand in the preceding four months.
• A collaboration lasting six months with Thai Union Group covers 12 square kilometers and targets removal of more than 3.2 tonnes.
• Koh Samui's E2C network produces about 100 bricks daily and has used more than 720 kilograms of recovered nets and plastic.
• Krabi's Second Life initiative, led by Wongpanit Krabi Co Ltd, works with more than 20,000 families on sorting, collection and processing.
• Seven retired platform jackets became artificial reef structures near Koh Phangan in 2020, at depths of about 38 to 40 meters.
• Koh Tao combines reef surveys, coral nurseries, cleanups and a legally backed tourist charge of 20 baht per visitor.
• AI supports debris detection and reef monitoring, while trained crews and suitable water conditions remain central to recovery.