Retired business executive Alexander Reisch plans to spend the next two months cruising the Mediterranean on his very own luxury yacht. In Gdansk, Poland, he collects his new vessel - a hybrid model that runs on diesel fuel as well as batteries powered by solar panels. But sailing without using diesel at all is still a thing of the future, as he finds out when he visits the Cannes Yachting Festival.

Meanwhile, in Ibiza, marine ranger Kike Navarro does his best to prevent large yachts and especially their anchors from damaging the ecosystem. On behalf of the environmental authorities, he takes his patrol boat from yacht to yacht, warning owners and captains not to damage the Posidonia seagrass meadows on the seafloor. These underwater forests are part of a UNESCO World Heritage Site. What’s more, they store massive amounts of CO₂ - more than the largest rainforests - performing a vital role in the fight against climate change.

And yet many yacht owners are either uninformed or indifferent to the issue. A group of climate activists known as Futuro Vegetal have decided to take action. Bilbo and Luna risk arrest and prosecution as they draw attention to what they say is the "eco-vandalism" caused by luxury yachts.

While cargo ships and cruise ships are obliged to gradually reduce emissions from 2025 onwards, many superyachts have so far remained practically immune from EU climate regulations. For Bilbo, a prison sentence would mean not seeing his two-year-old daughter grow up. But he cannot stand idly by. "If we don't do it, who will?" he says.