The South Coast turns the volume up fast. Visit Seljalandsfoss and Skogafoss, two of Iceland's signature waterfalls, and if you climb the stairs near Skogafoss, expect wind, spray and a strong reminder that nature is not trying to be polite. Continue to Reynisfjara, where black sand and sharp basalt formations make the coastline feel almost lunar. Later, reach Jokulsarlon Glacier Lagoon, then walk down to Diamond Beach, where broken icebergs wash onto black sand and catch whatever light the sky gives them.