Parisians Paul Guedj, 30 and Alexis Troccaz, 28, came up with the idea for their shoe brand, Corail, after noticing how many plastic bottles were in the sea.
Mr Troccaz said: “Making these trainers is a way of allowing thousands of people to have a real impact.”
They teamed up with local fishermen to collect plastic bottles from the sea around Marseille.
The bottles are sorted, washed and chopped into small pieces.
A machine then reduces them into a fibre which is transformed into yarn, woven in France.
There are five models of trainer available, with colour options of red, blue, pink and green.
Each shoe is handmade in Portugal, with the laces, soles, lining and fabric all made from plastic bottles.
Prices start at €99, and each pair can recycle up to eight bottles.
The firm also runs its own shoe recycling scheme. Owners can return well-worn shoes, which will be recycled to create new shoes and other objects.
The trainers are proving popular, with more than 2,690 pairs already sold – the partners’ original goal was to sell 300.
For more information, see ulule.com/basket-corail.