Photography: Craig Manley Giola, Thassos, Greece. The lagoon, located near the village Astris, is often called the most natural swimming pool. Indeed, it is a unique water reservoir, which provides a pleasant swimming experience. The Aegean Sea rinses its shores and fills the pool with water. But since the pool is separated from the sea with a rock wall, the water in the lagoon is much warmer, making it much more pleasant to dive in.