Proficiency in underwater communication is not only a vital part of scuba diving training, it also makes diving a much more enjoyable and safer experience. Scuba Diving Hand Signals intends to support beginning recreational scuba divers in learning underwater communication via hand signals. More than 240 commonly used gestures are illustrated and grouped into eight categories: Common signals Problem and emergency signals Training signals Air Pressure and number signals Underwater wildlife signals Environment signals Emotion signals Miscellaneous signals Underwater wildlife signals are accompanied by QR codes that provide access to supplemental online resources.