A traditional dhow sailing boat made entirely of trash has set off on an expedition along the Kenyan coast to raise awareness about the harmful effects of plastic waste.

Dhows, with their billowing triangular sails, are iconic on the Kenyan coast, having traversed Indian Ocean waters for some 2,000 years.

On Sunday, the dhow set off from the coastal town of Watamu for the fourth leg of a 500-kilometre expedition that began on Lamu island on Thursday and is set to finish in Zanzibar on February 6.