Thousands of oil spills have been recorded over the years, releasing large volumes of oil into marine ecosystems and causing lasting damage to biodiversity, fisheries, tourism and coastal economies. While major incidents attract attention, smaller fuel leakages and uncontrolled discharges, including diesel and similar pollutants, can be just as harmful when they go unnoticed.
At the same time, although facing fragile growth, rising costs and uncertainty, maritime transport remains central to global trade, making reliable monitoring and early detection more important than ever. As shipping activity continues to shape global commerce, improving the speed and accuracy of marine pollution detection is becoming an increasingly urgent priority.
It also reinforces the importance of frameworks such as the MARPOL Convention, which set the global standard for preventing pollution from ships.
Figure 1.Left: raw satellite image of the Odessa region, Ukraine. Middle: Coastal Intelligence operational interface output. Right: detected oil spill extent (red) on top of the river plume (green) — output for the client.
Why Fuel Spills Still Go Undetected
One of the biggest challenges is to detect not crude oil, but more volatile oil derivatives and fuel spill and leakage detection.
Moreover, not every suspicious patch on the sea surface equals pollution. Remote sensing operators must distinguish real discharges from naturally occurring phenomena that can look very similar in satellite imagery. These include biogenic slicks, low-wind areas, rainfall zones, internal waves and the leeward sides of islands.
That is exactly where advanced analytics becomes essential. SeaCras developed Coastal Intelligence, a tool that detects fuel spills with the combination of synthetic aperture radar and optical sensors, and different spatial resolutions of sensors. Coastal Intelligence utilises a series of additional atmospheric and marine data (often called auxiliary data) on a data fusion principle. This is a new methodology of deep learning that increases precision and detection rate of pollution incidents by reducing false positives in complex coastal environments.
Figure 2.Satellite-derived view of the incident in Hvar coastal region, showing the detected thin diesel leakage pollution intensity over the affected area, with warmer colors indicating higher surface concentrations of oil derivatives and the red outline marking the highlighted area of high pollution intensity area.
How Coastal Intelligence Improves Marine Pollution Monitoring
Coastal Intelligencecombines proprietary satellite imagery processing modules with an innovative data analysis approach to deliver more accurate results. The system achieves the best known commercial spill detection success rate, including for patches measuring only a few hundred square metres. By using different satellite technologies and different sources, SeaCras delivers operational services more frequently.
Our platform uses high- and very-high-resolution optical satellite data, enabling more precise monitoring even in smaller areas such as ports and marinas.
But its value goes beyond identifying oil-derived pollution. Coastal Intelligence also helps users distinguish between manmade pollution events, uncontrolled sewage discharges near port areas, and natural phenomena such as algal blooms. By combining satellite-derived water quality parameters, satellite images, and sea current vector field maps, the project’s partners have strengthened both their detection and identification capabilities.
This makes Coastal Intelligence especially relevant as a complementary solution to the European Maritime Safety Agency’s CleanSeaNet service, which supports participating states with satellite-based oil spill and vessel detection across Europe.
Figure 3.Satellite-derived view of the diesel spill in Baniyas coastal region, Syria. Left: very high spatial resolution analysis of the oil pollution showing the thin areas and small patches of pollution migration. Right: regional view of the catastrophe, showing the higher pollution levels depicted by warmer colors.
A Scalable Solution for Ports and Maritime Authorities
SeaCras has translated this scientific excellence and technical capability into a commercially available operational service. Today, Coastal Intelligence serves port operators and maritime authorities across the globe, which is an immense achievement, considering it was developed initially only for the Adriatic and Ionian regions.
Its added value lies in wide-area coverage, frequent and affordable monitoring as well as alert-based response support.
In practice, that means giving ports, authorities and coastal stakeholders a stronger chance to detect pollution early, respond faster and better protect the seas they depend on.
Other Marine Pollution Hazards and Unexpected Natural Events
Oil and fuel pollution are just a tip of the iceberg of a much broader range of marine and maritime threats. Floating marine litter, plastic pollution are some of the world’s largest problems, while climate change and warming of our oceans increase the occurrences of harmful and abnormal algal blooms.
Check out how Coastal Intelligence tackles those cases as well!
Our CEO, Mario Špadina, PhD, gave an interview to Slobodna Dalmacija after SeaCras was the first and only one to detect the Hvar oil spill!
Given the upcoming tourist season, it goes without saying we need to prevent such incidents, or at least predict them as early as possible.
That’s why, with our innovative early detection system, developed using satellite data, we are able to identify pollution while it is still in its initial phase. This system enables a rapid response that helps minimize damage and prevent long-term negative consequences for the marine ecosystem.
SeaCras technology enables the detection of large polluted areas, which is something that wasn’t possible before, and provides a chance for rapid intervention.
What we at SeaCras stand for is the proactive protection of the marine environment, as we believe that preserving the Adriatic Sea is the responsibility of all of us – institutions, the private sector and citizens.
For example, mass tourism is a topic that’s often mentioned in the context of pollution, and for a good reason. Tourism is one of the key sectors of our economy, so it’s essential that we maintain it at a high level, while at the same time pay attention to the protection of the sea as our greatest resource. It is clear that the large influx of tourists that we’ve had for years leads to major pollution events in the Adriatic.
The pollution off the coast of Hvar island was covered in a large number of media. Thank you to everyone who recognized the importance of this topic!
Our mission is to provide users with clear guidelines on the areas that are most sensitive and where it’s necessary to take precautions. There is no single answer to the question of what to do, because this largely depends on the specifics of the location, its size and various other factors. Therefore, our goal is to help everyone understand what they need to do and on time.
Pollution will always be there and it’s not easy to fight it, but the right measure is proactive preparation and preventive measures, at least with a year in advance. This is the reality we (have to) live with.
Big thanks to Slobodna Dalmacija for this interview and for recognizing the importance of our efforts in preservation of the Adriatic Sea as the most valuable resource of Croatia.
Using the SeaCras’s Coastal Intelligence system, which integrates artificial intelligence (AI) and satellite technologies, a thin layer petroleum derivative (fuel) slick was detected in the wider port area of Hvar, including part of the adjacent coastal waters. Here’s more about the recent Hvar oil spill in the article below.
According to the criteria outlined in Annex I of the MARPOL Convention (International Convention for the Prevention of Pollution from Ships, IMO), the identified pollution event qualifies as an accidental oil spill in the coastal zone.
In accordance with the Maritime Domain and Seaports Act (Official Gazette 83/23) and the Environmental Protection Act (Official Gazette 80/13, 153/13, 78/15, 12/18, 118/18), such an incident constitutes environmental degradation and mandates an appropriate assessment and response.
Note: This study refers exclusively to an internal study conducted by SEA CRAS d.o.o. The results will be published by the company’s scientific team in the form of a peer-reviewed scientific paper. The goal of this activity is to contribute to the conservation of the marine environment and ecosystem of the Republic of Croatia, and to enhance preparedness for future incidents, which, given the maritime traffic density of the Adriatic Sea, are likely.
Through the use of SeaCras proprietary technology, it was established that the spill consists of a petroleum derivative dispersed in an extremely thin surface film. The oil slick was observed on April 24, 2025, at 12:05 PM local time, in the area between the islet of Gališnik and the island of Hvar.
The spatial extent of the detected slick outside the Hvar port basin covers approximately 8 hectares (80,000 m²), and is illustrated in Figure 1.
Croatia and many of EU Member states still lack adequate monitoring capabilities for sudden pollution events affecting its territorial sea and internal waters
In the context of globally documented cases, it is important to emphasize that oil slicks of such small surface area are nearly undetectable using conventional monitoring methods. Specifically, the CleanSeaNet program of the European Commission, based on Sentinel-1 satellite radar (SAR) data, is incapable of detecting such phenomena for several reasons:
The spatial resolution of the available SAR data is insufficient – results are often too coarse for precise detection.
The use of Sentinel-1 radar imagery is not effective in enclosed, highly indented coastal zones, such as the waters around the Port of Hvar.
Complex coastlines like Croatia’s are characterised by diverse bathymetric and benthic properties and are full of small bays, narrow channels, and rocks in the sea, all of which hinder the use of traditional or most existing solutions available on the market.
Through the application of its proprietary technology, based on ultra-high spatial resolution satellite imagery analysis and AI-driven algorithms, SeaCras successfully detected petroleum derivative pollution in the form of an extremely thin surface film, covering a relatively small area compared to typical large-scale oil spills.
Nevertheless, even such a small detected slick constitutes an ecological incident with potentially long-term impacts on the marine environment of the area.
The SeaCras scientific team will continue with a detailed analysis of this incident and will propose mitigation and response measures aimed at protecting the wider affected marine area.
