What is happening in the diagram ;

*my attempt to describe.*
There is a modern sail boat on the surface of the water, point A is a set of waves (they look like the curved lines on per say your volume icon; ))) ) that go down to a boat wreck(point B) on the ocean's floor. Point C is another set of the waves going up to hit the bottom of the sail boat.
I believe it is some sort of set of vibrations being sent through the water but I do not know if there is sonar involved.
Help is greatly appreciated.

it appears that the sailboat is using sonar to locate the wreck

By the way those are not electromagnetic but acoustical.

Based on your description, there is a modern sailboat on the surface of the water, with waves (represented by curved lines) hitting the boat from two directions - one set of waves is coming down from point A and another set is going up from point C. This creates a scenario where the waves hit the bottom of the sailboat. Additionally, there is a boat wreck located at point B on the ocean's floor.

To understand what is happening in the diagram, it seems like there is some sort of interaction between the waves and the sailboat, potentially involving vibrations. However, without further information or context, it is difficult to determine precisely what is occurring.

To get a clearer understanding of the situation, you might need additional details or context about the diagram. This could include any accompanying text, labels, or symbols, or any related information you have about the topic being depicted in the diagram.

If you suspect that sonar is involved, you could investigate further by looking for additional clues or elements in the diagram that may indicate the use of sonar. Sonar is a technique that uses sound waves to navigate, communicate, or detect objects in the water, so if there are any indicators of sonar equipment or signals in the diagram, that could provide a possible explanation for the waves and their interaction with the sailboat and the wreck.

It may also be helpful to consult the source or creator of the diagram to obtain more information or clarification on its content and purpose.