Scientists have believed for many years that light does not penetrate below 200 meters of ocean water. What experimental method would best test this hypothesis, and why?

Scientists should sent a robot and observe the light penetration in the ocean water.

Explanation:

Robots in modern day have become a source of experiments for scientists. Many scientists believe that sending a robot is a better way for research as they can have different observation at different time for a certain period before making a final remark. The robots should be sent in ocean water and observations should be recorded on graph. These observations should be made in different timings to make the research more realistic.