This reminds me of the Butcher in the movie American Sniper. Perhaps the character was modeled after Soleimani.
It's a teather to the board. You can see it in the larger picture.
Hawaii. He's been there since Dec 16 according to this article.
https://www.msn.com/en-us/lifestyle/lifestyle-buzz/barack-obama-enjoys-a-paddleboarding-session-while-on-vacation-in-hawaii-but-ends-up-taking-a-tumble-into-the-water/ar-BBYAG3B?ocid=spartanntp