Lots of talk in the news today about the increased use of semi-submersibles in the drug trade. Million dollar fiberglass or steel vessels from South America transiting the Caribbean for the US Coast. Semi-submersibles are a lot stealthier and harder for the CG to pick up on radar. However, as you can see in the video from one of the busts, they are not invisible. The video is a little long but check out the second to last bust, about 5:00 minutes in. That's my favorite.