Wide Beaches during Low Tide in Las Grutas. Las Grutas is a beach resort town located in the Argentine province of Río Negro, in the department of San Antonio, with a stable population of 8,000 inhabitants. It’s located 15 kilometers south of San Antonio Oeste, and is visited by over 400,000 tourists every summer. Its beaches are known for having relatively warm waters in spite of their location in the Patagonia, due to the wide tidal amplitude, and the protection of the San Matías Gulf. The town was founded in 1964, mainly as a group of campings, and soon began growing. But it was not until the 1980s that tourism industry finally exploded, with the construction of numerous apartment and a casino. southern right whales are seasonal residents and visit here. Las Grutas’, meaning “The Caves” in Spanish, comes from the caves created by the erosion of the sea on the cliffs that separate the city from the beach. 4K Resolution.