The next day we went to a beach in Playa Los Acantilados, south from Mar del Plata. We took a local bus and we travelled for 1hour 30minutes. But it was worth it, the beach was not too crowded and there were no buildings and no hotels near the beach, just some rocks. I enjoyed this beach too, although in the evening it became very windy and cold. Mar del Plata is known for its "crazy" weather, with significant temperature swings and extreme weather. The city is exposed to contrasting air masses and frontal storms, leading to variable temperatures and weather conditions. The region experiences the influence of both warm, humid air from the Atlantic Ocean and cooler, drier air from the interior, creating a dynamic and unpredictable weather pattern. Frontal storms, where different air masses collide, bring sudden changes in temperature, precipitation, and wind conditions. 

The bus ticket (using the Sube travel card) costs $1.3 here, when in Buenos Aires it cost me less than $1 (60 pence) and the local people in BA pay half. In Mar del Plata, everyone (both the local people and tourists) pay the same, $1.3 (= 1,300.00 pesos).