Curdled oil was found across the Vung Tau beach in the southern province of Ba Ria-Vung Tau on March 2.
Locals have been using shovels, rakes and bags to collect the oil and minimise any negative impacts on tourism.
Curdled oil has regularly appeared and spread along the coastline of Vung Tau during March and April, though it is expected to be unusually heavy this year.
The cause of the phenomenon has not yet been identified.