Of the tens of thousands of ships on the ocean bottom, only a handful, less than 1 percent, contain negotiable treasure, such as gold and jewels. 

    Most give us a different priceless treasure -- history. A sunken ship lies in trust, preserved in the airless environment of the sea and those in deep water are especially well protected. No dry land sites anywhere -- except perhaps Egyptian tombs -- are in a better state of preservation than a vessel deep in the ocean. A sunken ship, therefore, can be a rare window through which a moment in time is glimpsed. 

    This is not to imply that sunken ships are always found intact. Most ships break up on the way down, hit the bottom at about 100 miles per hour, and become a chaotic, confusing jumble. I recall the chagrin of a novice diver who, after surfacing from an underwater tour of a 400-foot ship, asked his diving buddy, "Where was the wreck?" It takes experience to actually know a sunken ship when one sees it. But no matter what its condition on the way down, a ship deteriorates much more slowly as it sinks deeper into protective layers of sand and mud. Ancient vessels have been found in remarkably good condition. In 1977 a group of marine archaeologists excavating a 900-year-old wreck recovered engraved glassware. Greek coins, bronze kettles, and amazingly, Greek jars containing seeds, almonds, and lentils -- even a plate with chicken bones. 

    在數以萬計的海底沉船中，只有極少數，不到百分之一的沉船上有可流通的財富，如黃金和珠寶。 多數沉船提供給我們的是另一種無價的財富--歷史。

     沉船被海洋中沒有空氣的環境保管起來，躺在深水中的船只被保存得尤其完好。 大概除了埃及金字塔外，陸地上沒有哪些遺跡比深海沉船保存得更完好了。 因此，每一只沉船便成為我們探視歷史的一扇難得的窗戶。

    但這并不是說沉船被發現時都完好無損。 大多數船只在下沉過程中就已破碎，并以每小時100英里的速度撞擊海底，因此成為亂糟糟的一團。 我至今仍記得一位潛水新手造訪一艘400英尺長的海底沉船后浮出水面時的懊喪神情。他問他的潛水伙伴："沉船在哪兒?" 看到沉船時能知道這是一只沉船是需要經驗的。 但不管船在下沉時狀況如何，當它下沉到海底具有保護作用的泥沙層后，船體的朽爛速度比在陸地上要慢得多。 人們曾在海底發現過保存異常完好的古船。 1977年，一群海洋考古學家們在發掘一只有900年歷史的沉船時，找到了雕花玻璃器皿、希臘硬幣、青銅水壺，并令人吃驚地發現一些盛有種子、杏仁和扁豆等東西的希臘罐子，甚至找到一個盛有雞骨的盤子。