These ancient cities sunk to the ocean floor. Here's how they were rediscovered.
Located in the southern Peloponnesian peninsula, Pavlopetri (the modern name of the site) emerged as a Neolithic settlement around 3500 B.C. and became an important trading center for Mycenaean Greece (1650–1180 B.C.). This area of the Aegean Sea is prone to earthquakes and tsunamis, which caused the city to gradually sink. The slow sea level rise in the Mediterranean submerged the city more than 3,000 years ago.
For millennia, the city's remains lay unseen below some 13 feet of water. They were covered by a thick layer of sand off the island of Laconia. In recent decades, shifting currents and climate change have eroded a natural barrier that protected Pavlopetri. In 1967 a scientific survey of the Peloponnesian coast was gathering data to analyze changes in sea levels when British oceanographer Nicholas Flemming first spotted the sunken structures. A year later, he returned with a few students to examine the location and map the site. The team identified some 15 buildings, courtyards, a network of streets, and two chamber tombs. Despite the exciting initial finds, the site would lie undisturbed for decades before archaeologists would return.
In 2009 archaeologists Chrysanthi Gallou and Jon Henderson resumed the excavation of Pavlopetri in cooperation with the Greek Ministry of Culture. Since the 1960s, underwater archaeology techniques and tools had made huge advances. The team employed robotics, sonar mapping, and state-of-the-art graphics to survey the site. From 2009 to 2013 they were able to bring the underwater town to light. Covering about two and a half acres, Pavlopetri's three main roads connected some 50 rectangular buildings, all of which had open courtyards. Excavations revealed a large number of Minoan-style loom weights, suggesting Pavlopetri was a thriving trade center with a robust textile industry.