The beach at Cala Santanyí is crowded by tourists in the months of July and August usually. To avoid the hustle and bustle of tourists, it is better to come in the low season (May to June or September).
Want to take a swim in the ocean or to sunbath at the beach? Traveling to Mallorca in May/June or September is perfect because it is in the low season (cheap!), plus the water and air is still warm enough for swimsuits.