In our imagination, a dive in the seas washing the shores of the island of Bali, in Indonesia, can only evoke crystal-clear waters, multicoloured marine life and lush seabeds. Yet this is not the spectacle that confronted British diver Rich Horner.

At 65, he plunged into the sea around the island of Nusa Penida with the aim of filming manta rays. But he found himself swimming, literally, in a sea of plastic. The video he published is simply terrifying: the man found himself in the middle of hundreds of pieces of waste. "Ocean currents have brought jellyfish, plankton… and plastic!", the diver said, as reported by the French newspaper Novethic.

The sea of plastic travels through the Indian Ocean

Horner also reported that the following day other divers carried out dives, finding nothing, however: "The plastic continues its journey through the Indian Ocean. So it will break down into ever smaller pieces, until it becomes microplastic." Ending up being ingested by fish and seabirds, thus entering the food chain and going on to contaminate humans as well.

In 2016, a study carried out by the Ellen MacArthur Foundation together with the McKinsey Center for Business and Environment had explained that the ratio between the tonnes of plastic present in the oceans and those of fish — currently one to five — will become one to three as early as 2025. Then, a quarter of a century later, the crossover will occur: the quantity of fish in the sea will be lower than that of plastic waste.