Many kinds of treasures are found in the world's oceans. These oceans are so difficult to explore, however, that many oceanographers believe scientists know more about Mars than the environments below the earth's ocean surface. Underwater explorations have a long history. In 1620, Cornelius Drebell sailed his submarine, a rowboat covered with leather, in the river Thames. Early scientists dragged buckets on ropes across the ocean floor, scooping up sediment, minerals, deep-sea fish, and plants-natural treasures of the sea. Select an ocean that interests you. What can you find out about organisms that live in one area of that ocean?