While there last week, the northern Anegada beaches were covered with it. Anegada Beach Club had a guy with a 33 gallon trash can raking it up as fast as he could, and we were able to get to the water without treading through it. However, Lobolly was a different story. It was 1-2' tall and 3-4' thick through much of the area.
Areas on Tortola where the water was calm and it congregated had a pretty strong smell.
On the water, sailing through it was not a problem and we didn't see that much of it.