Is easiest to make under most underwater conditions. Can be made with one hand, when a sign is available. Unfortunately, there is no universal sign language.
Many countries have their own sign language.
ASL has been used by people in the U.S. for almost 200 years. Signs may represent words, phrases, or concepts. Signs have evolved over time into forms which are easy to make and understand. Signed English , is a signing system using one sign to represents one English word. Wherever possible in this system ASL signs are used, so the systems share much of the same vocabulary.