Thousands of policemen and coast guard officers were put on alert yesterday as droves of holidaymakers left cities around Greece, headed to their summer vacation destinations by road and sea. There were no major problems for travelers despite the high numbers of cars on the road and passengers waiting to catch ferries at the country’s ports. The Merchant Marine Ministry estimated that yesterday alone some 100,000 people embarked on ships from Rafina and Piraeus. More than 280 ferries are due to leave the two ports between today and Tuesday. However, officers are to stay on alert as a number of holidaymakers, who left on vacation earlier this month, are expected to begin making their way back on Tuesday. Traffic police said they expect next Sunday to be the busiest day of the summer on the roads.