<span>In the 20th century, the scientist believed
that the floor of the ocean floor is flat. But later on discovered that their
theory is wrong. The ocean floor is not flat and featureless. One technology
helped the scientist to study in advance and in details the real feature of the
ocean floor. They used sound waves to know the distance of the water from floor
level to the top. They also discovered that ranges of mountains lies under the
ocean. Sonar was one of the technologies they used to study the sound waves
emitted by the ocean.</span>
