Thank you simplejoy 🙂
We were on a cruise ship anchored off Port Vila, Vanuatu. The sunsets and sunrises were amazing.
I hadn't noticed the "tiny black triangles in the water" before you mentioned them 🤔 so I zoomed in on the original and I can see they are some kind of marker buoys. They look way too small to be shipping channel markers so I am not sure what their purpose is.
Below is a crop of zooming in on one of them.