More and more pleasure boats are plying the French Mediterranean coastline. To such an extent that they are threatening a key ecosystem: the Posidonia meadows. In sharp decline in the most popular tourist areas, these could disappear within 10 or 15 years. After confinement, this summer’s tourists got the word out: all aboard their boats. Pleasure boating boomed this summer compared with previous summers. The authorities are now pulling out all the stops to protect this precious ecosystem, considered to be the richest on the planet in terms of ecosystem services rendered. Without Posidonia meadows along our Mediterranean coasts, goodbye fish, beaches, translucent waters and… tourists!