But the first and foremost reason is the quality of water. In winter you will find exceptionally beautiful and crystal clear water at beaches. While in summer the water is very much dusty and unclean.

While "summer" is the traditional answer, the "Shoulder Season" (late spring or early autumn) is widely considered the best time to visit the beach for a high-quality experience. In the Northern Hemisphere, this means June or September. During these months, the weather is typically warm enough for swimming, but you avoid the extreme, oppressive heat of July and August. More importantly, the massive crowds of school-holiday travelers have either not yet arrived or have already departed, leading to lower hotel prices and more available space on the sand. September is particularly prized because the ocean has had the entire summer to warm up, meaning the water temperature is often at its peak even as the air begins to cool slightly. If you are visiting tropical destinations like the Caribbean, the "best" season is the Dry Season (December to April), which avoids the humidity and the risk of hurricanes. Ultimately, the best season is one that balances comfortable water temperatures with manageable crowd levels and lower precipitation, making the late-spring "window" the sweet spot for most coastal travelers.