The chef who worked for the Obamas, recently drowned, and rescue person said looked. like blunt trauma on the face or head. Thinking about this, could be result of a collision with another jet skier, hit by a boat, hit rocks, something like that. Looking at google maps, the area of beach there looks to be sandy, not to say there couldn't be rocks just below the water.
Per this article, area of Obamas house is "The expansive 6,892-square-foot house sits on nearly 30 secluded acres fronting the Edgartown Great Pond between Slough Cove and Turkeyland Cove, with views of the Atlantic ocean".
https://www.homesandgardens.com/news/president-obama-new-house-marthas-vineyard
This whole thing is so Clinton-esque.