The Blue Caves in Zakynthos, Greece, are a stunning natural attraction. These sea caves are famous for their mesmerizing blue waters and the ethereal light effects created by sunlight reflecting off the white limestone and the sea. 

The name "Blue Caves" comes from the intense blue hues that illuminate the water inside the caves. This is caused by the reflection and refraction of sunlight entering the caves, creating a surreal, glowing blue effect. 

The caves are carved into white limestone cliffs and feature arches, tunnels, and hollows that make them ideal for exploring by boat or even swimming and snorkeling (in calmer conditions).