An artificial reef is a man-made structure that is built to promote marine life in the area. When snorkeling at Key Largo, one of our largest artificial reefs is the Speigel Grove site, which is a Landing Ship Dock that sunk in 2002, creating its own reef system. The ship is full of hundreds of tropical fish, coral, and sponges, twisting and combining itself with the human-made structure. It is a mysterious and challenging site for those who want to test their skills. This is one artificial reef you won’t want to miss!