What types of signal systems can divers use underwater?

Divers utilize a variety of signal systems to communicate effectively underwater due to the challenges presented by the aquatic environment. The correct answer encompasses fundamental methods such as hand signals, which are crucial for conveying information quickly and efficiently in an environment where sound does not travel effectively. Dive slates, which provide divers a means to write messages or draw diagrams, are also essential for more complex communications that cannot be easily captured through hand signals alone. Illumination signals, such as the use of dive lights to signal or indicate specific messages, add another layer to effective underwater communication, particularly in low visibility conditions.

Thus, the combination of hand signals, dive slates, and illumination signals allows divers to communicate critical information clearly and allow for emergency signaling or coordination of activities in a reliable manner.