First, as you travel along the Great Harbor, keep your eyes open for large columns and statues.

首先，當你沿著大港旅行，記得睜大眼睛注意那些大列柱和雕像。

Across the bay to your left is the island where the Great Lighthouse once stood.

穿過海灣，你的左邊是一個曾經有大燈塔佇立的海島。

And as you make your way through the palaces of the Royal Quarter and reach the area where the Library of Alexandria once stood, keep your eyes open for sharks.

然後當你走過皇宮，並到達曾經是亞力山大圖書館的區域，張大眼睛注意鯊魚。

Because if you visit this section of Alexandria, you'll be fifteen feet deep in the Mediterranean Sea.

因為當你參觀亞力山大帝國的這個地區，你是在 15 尺深的地中海中 。

Though people are most familiar with Plato's fictional Atlantis, many real underwater cities actually exist.

儘管人們最熟悉的是柏拉圖編造的亞特蘭提斯，但其實許多水下城市是真的存在的。

Places like Alexandria, Port Royal Jamaica, and Pavlopetri, Greece.

像是亞力山大港、牙買加的皇家港、 希臘的帕夫洛彼特里。

Sunken cities are studied by scientists to help us understand the lives of our ancestors,

科學家研究沉於水面下的城市，讓我們了解我們祖先的生活、

the dynamic nature of our planet, and the impact of each on the other.

我們星球上多變的自然環境，以及對彼此的相互影響。

Water is essential for life, food sources, and transport, so many cities have been built along coastlines and river banks.

水對於生命、食物資源及交通是不可或缺的，所以許多城市都會沿著海岸線和河岸建造。

However, these benefits also come with risks because natural forces that can sink a city are at their doorstep.

但這些好處也潛藏危機，因為可以使城市淹沒的大自然力量近在咫尺。

Take, for instance, an earthquake.

例如地震。

June 7, 1692 seemed like a normal morning in Port Royal, Jamaica, then one of the richest ports in the world,

西元 1692 年 6 月 7 日，在世界上最富有的港口之一 —— 牙買加的皇家港看似跟往常一樣的早晨，

but when a massive earthquake struck, two-thirds of Port Royal immediately sank to its rooftops.

但是當一個超級大地震來襲，三分之二的皇家港便瞬間沉沒滅頂。

Today, many buildings and elements of everyday life remain surprisingly intact on the sea floor, frozen in time.

今天，很多建築和日常生活的元素仍令人驚訝地、原封不動地保存在海底，時間彷彿凍結了。

That includes a 300-year-old pocket watch that stopped at 11:43, the moment Port Royal slipped beneath the Caribbean.

包括一只三百年前的掛錶，時間停留在 11:43，也就是皇家港沉到加勒比海下的時刻。

And during the winter of 373 BCE, the Greek city of Helike was struck by an earthquake so strong that it liquefied the sandy ground upon which the city was built.

另外，在西元前 373 年的冬天，希臘的赫里克城受到強烈地震的侵襲，使得城市建設下的土壤液化。

Minutes later, a tsunami struck the city, and Helike and its inhabitants sunk downwards into the Mediterranean Sea.

幾分鐘後，城市受到海嘯侵襲，赫里克城和其居民全都沉到了地中海。

Centuries later, Roman tourists would sail on the lagoon that formed and peer down at the city's remains.

過了好幾世紀，羅馬觀光客會在後來形成的潟湖航行，並且往湖裡看見城市的遺跡。

Earthquakes are sudden, unpredictable disasters that have drowned cities in an instant.

地震是突然且無法預知，並且可以使城市瞬間沉沒的災難。

Luckily, however, throughout history, the majority of sunken cities were not submerged by a single cataclysmic event, but by a combination of more gradual processes.

然而幸運的是，縱觀歷史，大部分被淹沒的城市並不是因為單一劇烈變動的事件造成的，而是一連串漸進的過程。

For instance, Pavlopetri, the oldest known sunken city, was built on the southern coastline of Greece 5,000 years ago.

例如，已知最古老的海底城鎮，帕夫洛彼特里城在 5000 年前建在希臘的南方海岸線上。

It's an example of a city that was submerged due to what is called isostatic sea level change.

這個城市是因所謂地殼均衡的板塊運動而淹沒的一個例子。

18,000 years ago when the Ice Age ended, glaciers began melting and the sea level rose globally until about 5,000 years ago.

一萬 8000 年前冰河時期結束，冰河開始融化，全球海平面持續上升，直到大約 5,000 年前才緩和。

Isostatic sea level change isn't caused by that melt water,

地殼均衡的板塊運動並不是融化的水造成的，

but rather the Earth's crust slowly springing back from the released weight of the glaciers, making some places rise, and others sink.

而是因為地球的板塊隨著冰河重量的釋出而彈起，使得有些區域上升，有些則下沉。

The ground around Pavlopetri is still sinking at an average rate of a millimeter per year.

帕夫洛彼特里城周圍的土地，至今仍在以每年平均一毫米的速度下沉中。

But the ancient inhabitants were able to move gradually inland over several generations before they finally abandoned the city about 3,000 years ago.

而古代的居民幾個世代以來，得以移往內陸。直到 3,000 年前，他們終於離開這座城。

Today, divers swim over the streets of Pavlopetri and peer through ancient door jambs into the foundations of houses and community buildings.

今天，潛水者游過帕夫洛彼特里城的街道，並且透過老舊的門側柱可以看見房子的地基和社區建築。

They learn about the people who lived there by observing what they left behind.

透過觀察人們留下的東西，可以了解當時當地居民的生活。

Natural geological events, such as earthquakes and tsunamis, will continue to shape our continents, just as they have for millions of years.

自然地理現象，像是地震及海嘯，將會持續影響我們所居住的大陸，如同這幾百萬年來一樣。

As increased global warming melts our polar ice caps at accelerated rates and sea levels rise,

當地球暖化加劇，造成極地冰帽快速融化以及海平面上升，

we will be forced to adapt, like Pavlopetri's inhabitants.

我們將被迫適應這個環境，就像帕夫洛彼特里城的居民一樣。

Undoubtedly, over the coming centuries, some of the coastal areas that we live in today will eventually be claimed by the water, too -

接下來的幾個世紀，毫無疑問地我們現今所住的海岸地區，也終將被海水淹沒。

cities like Venice, New Orleans, Amsterdam, Miami, and Tokyo.

像是威尼斯、紐奧良、 阿姆斯特丹、 邁阿密、 以及東京。

Imagine what future civilizations will learn about us as they swim around the ancient ruins of the cities that we live in today.

想像一下，未來的文明游過我們現在居住的城市廢墟周圍，會怎麼認識我們。