For Ulysses, the Mediterranean Sea was a world of danger, love, and destiny. From six-headed monsters to captivating sirens and unpredictable gods, each island on his journey home held a new adventure.
More than 2500 years after Homer's epic poem was first recounted, Christopher Nolan's The Odyssey has brought this journey to the world's biggest screens. But beyond the spectacular cinematic narrative, there is another protagonist undergoing its own odyssey: the sea itself.
Since the time of Homer, the Mediterranean has been much more than a beautiful expanse of water. Situated between Africa, Asia, and Europe, it has served as a waterway connecting cities, civilizations, and trade routes. It has also provided food and livelihoods and has played a central role in culture, spirituality, and the spread of ideas.
With over 500 million people currently living along its shores, in addition to some 25 coastal metropolitan areas, the importance of the Mediterranean has only grown. Today it supports enormous industries such as fishing, tourism, and shipping —it is home to some of the world's busiest shipping lanes—as well as a growing number of other activities.
It also constitutes an extraordinary ecological treasure. Although it represents barely 1% of the world's ocean surface, it is home to up to 18% of all known marine species, and more than a quarter of them are found nowhere else on the planet.
Underwater priests
The underwater meadows of Posidonia oceanica, an endemic marine plant whose name refers to the Greek god Poseidon and which is also known as Neptune's grass, cover more than 1,2 million hectares. They provide habitat for numerous marine species, capture carbon, and contribute to the nutrient cycle. Coastal ecosystems, such as salt marshes, wetlands, and dunes, protect the approximately 46.000 kilometers of Mediterranean coastline and its communities from erosion and storms. These landscapes provide food, water, jobs, and identity, but they are under increasing pressure.
The new monsters of the Mediterranean
Every day, approximately 730 tons of plastic waste enter the Mediterranean , much of it carried by rivers. Each year, these rivers deposit up to 925 million floating objects into the sea, of which around 82% are plastic. Single-use plastic products also account for more than 60% of the waste found on Mediterranean beaches.
Wastewater, industrial chemicals, agricultural runoff and pollutants from ships also affect the waters of the Mediterranean, along with more recent threats such as pharmaceutical waste, microplastics, plastic additives and underwater noise that disturbs wildlife.
As the recurring heat waves each summer demonstrate, the Mediterranean region is warming 20% faster than the global average. This phenomenon, combined with changes in rainfall patterns, rising sea levels, and ocean acidification, intensifies the threats of droughts, wildfires, floods, erosion, and water scarcity.
The extraordinary biodiversity of the sea—which includes loggerhead turtles, striped dolphins, swordfish, octopuses, and the rare Mediterranean monk seal, among many other species—is also declining as construction, pollution, and various industries alter and damage their habitats. As large predatory fish become scarce, fishers are increasingly catching smaller species lower in the food chain, thus disrupting the food web. Non-native species also displace native fauna when they arrive via shipping, aquaculture, and other activities.
These challenges often reinforce each other. Degraded coastal ecosystems offer less protection against storms and flooding. Rising water temperatures can facilitate the spread of invasive species and negatively impact biodiversity and native ecosystems. Irresponsible tourism generates ever-increasing waste and puts additional pressure on fragile habitats. While Ulysses typically faced his monsters one by one, the “villains” of today’s Mediterranean act in concert, eroding the overall health of the region.
An action plan for the Mediterranean
Fortunately, the sea also has an ally: the United Nations Environment Programme's ( UNEP /WFP) Mediterranean Action Plan. Created in 1975, it was the first regional action plan established under UNEP 's Regional Seas Programme , which now brings together 145 countries to protect the world's seas and oceans. In 1976, the Mediterranean countries adopted the Barcelona Convention, which constitutes the region's main legally binding framework for protecting the marine and coastal environment.
Twenty-one Mediterranean countries and the European Union work together through UNEP/WFP and the Barcelona Convention. While the protocols are legally binding under the Convention, UNEP/WFP helps countries agree on common standards, monitor marine health, and translate regional commitments into national measures.
To this end, it supports countries in reducing plastic and chemical pollution, improving wastewater management, and preparing for potential threats such as oil spills. A regional plan to prevent and manage marine litter, adopted in 2013 and updated in 2021, was the first legally binding framework of its kind and committed parties to reducing and eliminating marine debris and incorporating circular economy approaches.
UNEP/PAM also supports marine protected areas and action plans aimed at preserving biodiversity and threatened habitats (including Posidonia oceanica seagrass meadows), promotes the restoration of degraded ecosystems, and helps countries identify and control pathways for invasive species. Under the program, specially protected areas have been established covering more than 8% of the Mediterranean, as well as specific protection plans for certain species, including the Mediterranean monk seal.
As temperatures and climate risks rise, UNEP/WFP also advises countries on smart coastal planning , focusing on restoring and maintaining natural defenses such as dunes and wetlands. Its work on sustainable production and consumption, tourism, ports, and marine spatial planning also aims to help Mediterranean economies grow while protecting the ecosystems that have sustained the region's prosperity since antiquity.
Unlike Odysseus's return to his home on the island of Ithaca, the Mediterranean does not have a single destination at the end of its odyssey. But there is a clear vision for the future of this sea. “What we are striving for is a healthy and prosperous sea, whose magnificent wildlife, ecosystems, and industries can sustainably support the millions of people from numerous cultures who call this region home,” said Tatjana Hema, program coordinator.