Playa Negra is a fairly narrow black sand beach near Esperanza on the island of Vieques in Puerto Rico. The black sand is very fine and gets burning hot in the sun.  Lots of sargassum, seaweed from the Sargasso Sea has washed up on the beach, obscuring much of the black sand.
<a href="//commons.wikimedia.org/wiki/User:Lorax" title="User:Lorax">G. Edward Johnson</a>
CC BY 4.0
<span class="int-own-work" lang="en">Own work</span>