Found a much smaller garbage patch in the SW Caribbean recently. We were about 100 miles from the western end of the San Blas Islands in Panama and ran into a large region of sargasso weed and plastic. Took us several hours to cross it. Apparently the currents from the east swirl here and plastic comes from all over the Caribbean until it finally is carried west along the coast of Colombia and Panama. Nasty looking to be sure.
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.