1. Most of the world′s surface is . We may know the land very well, but we know very little about the oceans.
Until recently, man could not stay underwater for long. A pearl , for example, couldn′t stay underwater for longer than two minutes. But now, with special breathing equipment, a diver can stay underwater for a long time. After the of this equipment, man could swim freely underwater and scuba-diving became a popular sport.
A Frenchman, Jacques Cousteau (1910 - 1997), invented a deep-sea diving in the early 1940s. In the vessel, he could explore the oceans of the world and study underwater life.
Now, we can explore the , using special TV cameras as well. We can learn more about the undersea world thanks to this invention.