An environmentalist has stopped his attempt to swim across the Pacific Ocean, which was to take him through the Great Pacific Garbage Patch, after technical difficulties hit his support vessel.

Ben Lecomte had completed some 2,780 kilometres of his 9,260-kilometre journey when the decision to abandon the swim was made due to a damaged mainsail, he wrote in a statement published Monday by science media company Seeker.

"The Swim has been challenging for us as we've continued to face treacherous winds and ocean swells. Unfortunately our sail suffered irreparable damages, forcing us to alter our course and timing," the French-American wrote.

"Safety is our number one priority, and at this point, the team is exploring all options in an effort to continue into the gateway of the Garbage Patch."

The 50-year-old left Japan's Pacific coast on June 5 heading for San Francisco before being forced to turn back due to violent storms.

He eventually took to the water again and had been swimming up to 8 hours a day with the aim of covering 1,600 kilometres of the Great Pacific Garbage Patch. He and his team had collected over 1,000 samples of the water to determine levels of plastic pollution.

The Great Pacific Garbage Patch is a floating accumulation of over 80,000 tonnes of plastic debris and other pollutants in the North Pacific Ocean.

Scientific Reports journal said in March that it covered an area of 1.6 million square kilometres and was growing exponentially.