Interesting idea. I like it because it will act like a wall to make crossing the border harder. Any passenger ferries bringing illegals across could be sunk easily enough. It's a win-win. The cost doesn't matter, whatever it takes. It would give us better trade sovereignty. Right now, the Panama canal is controlled by the Chinese. Security isn't a problem since under water mines could easily be placed in strategic locations and activated when needed. The locks could also prevent hostile ships from entering or leaving.