Cessna 206 pilot reported safely diverting to an alternate airport after experiencing loss of manifold pressure.

Narrative

As I was descending to 9;500 feet; my aircraft began experiencing loss of manifold pressure from 27in of manifold to 23in of manifold with no manipulations of the controls. I began to immediately troubleshoot the issue and made the decision to find the nearest airport. I knew that I had a few airports in the vicinity to my 7 o'clock so I immediately turned towards that heading. I immediately called up ZZZ Approach to but I could not get them to respond; so I then switch to ZZZ1 Tower frequency. I proceeded to give ZZZ1 my location; altitude; and distance from the airport (11 miles); and they gave me priority for any runway. Coming from the north I decided to give myself a straight in approach to runway XX. During the descent to the airport I observed the manifold pressure drop and spike from 27in to 23in at least 2 times. As I descended I realized very quickly that I needed to make one descending 360 to lose the appropriate amount of altitude for a safe and stable landing. I was able to successfully land on runway XX with no injury to personal or damage to the aircraft. Once grounded and engine turned off I was met by the responders of the airport and gave them a statement of the incident.