Answer
In summer, the population and the demands placed on Punta del Este increase sharply as tourists arrive from Uruguay, Argentina, Brazil, and other countries. But a figure of "one million people" without a specified period or area is misleading: it may refer to visitor numbers over a season or in the region, rather than the number of people simultaneously in the city.
In practice, high season means expensive rentals that book up quickly, heavy traffic, queues at popular spots, and the need to reserve restaurants and activities. Demand peaks over the New Year period and during certain summer weeks rather than being spread evenly.
If beach services and events are important, book in advance. For a more relaxed trip, choose the end of February or the off-season, checking whether establishments are open. For up-to-date statistics, consult the Ministerio de Turismo and the authorities of the Maldonado Department.