On a winter night in 373 B.C., a massive earthquake triggered a tsunami that engulfed the Greek city of Helike, submerging the busy cultural center and its inhabitants. For centuries, the story of Helike and its demise—known only through descriptions by classical writers—was interpreted as legend; still, archaeologists trawled the Corinthian Gulf for traces of the lost metropolis, hoping to find a snapshot of Greek civilization at its height and frozen in time. In 2001 researchers finally unearthed ruins and artifacts from Helike at an inland site, showing that a lagoon—not the ocean—covered the city after its destruction and subsequently dried up. Some scholars believe the real-life events at Helike inspired Plato to write about the fabled island of Atlantis.
Roughly 3,000 years ago, the Bronze Age port of Pavlopetri, located on the southern coast of mainland Greece, slipped beneath the waves as a result of gradual erosion, a tsunami or other mysterious factors. It was discovered in 1967 under less than 15 feet of water. In 2009 underwater archaeologists produced a complete digital map of Pavlopetri’s ruins, which include public buildings, residences, courtyards, streets and graves. Like the more recent Helike, Pavlopetri might have served as a model for Plato’s mythic Atlantis, some scholars believe.
A bustling shipping hub in southeastern Jamaica, Port Royal was founded by the Spanish in 1518 and captured by the English in 1655. Pirates and privateers flocked to the Caribbean city in the late 17th century, providing steady business for brothels and bars while earning Port Royal a wicked reputation. When a disaster of biblical proportions struck in 1692, some observers predictably likened the center of sin to Sodom and Gomorrah. Just before noon on June 7, an earthquake rattled Port Royal, causing the sand on which it was built to liquefy. Buildings and streets slid into the sea, creating what is now considered one of the western hemisphere’s most significant underwater archaeological sites. Thousands of people died in the disaster, and later attempts to rebuild Port Royal were stymied by tremors, fires, hurricanes and other catastrophes.
Now home to hammerhead sharks, a remarkable site off the coast of Japan’s Yonaguni Island has perplexed archaeologists and other experts since its chance discovery in 1987. Known as the Yonagumi Monument, it consists of a submerged stone pyramid reminiscent of temples in ancient Mesoamerican cities, surrounded by other structures resembling pillars and walls. The monument’s staircase-like features and sharp angles have led some theorists to speculate that human builders had a hand in the stunning underwater display, perhaps back when the region stood above sea level during the last Ice Age. Others maintain that the monument is entirely natural and consistent with typical sandstone erosion patterns, or that prehistoric people refurbished it by modifying an existing rock formation.
Located on the Bay of Naples, the seaside resort of Baiae once attracted wealthy ancient Romans with its thermal springs, swimming pools, casinos and pleasant climate. Numerous rulers and dignitaries built magnificent villas there, including Julius Caesar and Nero; according to legend, it was also the site of Caligula’s floating bridge stunt in 39 A.D. Baiae was abandoned during a malaria outbreak in the 16th century, many years after its heyday. Volcanic activity has since caused the ancient city’s ground level to sink, plunging its ruins under water.