About 650 thousand people.

Mar del Plata is Argentina's most popular beach city, right on the Atlantic Ocean. In summer, millions of families come to enjoy the sand, sun, and sea.
You can build sandcastles on long beaches, watch playful sea lions at the port, and eat fresh churros dipped in chocolate. There is also a fun harbor with colorful fishing boats.
Mar del Plata has miles of sandy beaches where families swim, surf, and play all through the warm summer months.
At the old port you can see a colony of big sea lions basking in the sun and barking loudly, a favorite sight for kids.