Well, they often use hand signals, such as the “OK” sign, and sometimes they write on message boards. So much for how SCUBA divers (classified as animals) communicate! Other than the authors’ knowledge of sound waves and how they move air and water, along with the fact that whales and dolphins make cool sounds, SCUBA diver communication was about the extent of his understanding of how animals’ communicate underwater. So, he did a bit of research and discovered lots of interesting things, which he shares in this month’s column.