Which of the following options is NOT a method for communicating underwater?

The correct answer is that "talking" is not a method for communicating underwater. Underwater environments pose significant challenges for vocal communication; sound travels differently in water compared to air, and human voices do not carry well, making it difficult to be understood. The sound waves can become distorted, and other noises in the water can drown out speech, rendering it ineffective for clear communication during dives.

In contrast, using lights as a method of communication relies on signaling, where divers can convey messages through different patterns or colors of light. Writing in a waterproof slate is a common practice for sending messages, especially when silence is essential. Hand signals are also widely employed among divers, allowing for a variety of gestures to express different messages or commands, ensuring effective communication in the underwater setting.