When is a buddy line specifically required?

A buddy line is specifically required in low visibility or night diving because these conditions can significantly impair a diver's ability to see their buddy or the surrounding environment. The use of a buddy line ensures that divers can stay connected and maintain physical contact even when visibility is compromised. This increases safety, as the buddy line allows divers to assist each other more effectively in difficult conditions, thereby enhancing communication and support.

While the other scenarios provided may benefit from the use of a buddy line, such as during surface swimming or when conducting underwater repairs, they do not necessitate it in the same critical way as low visibility or night diving does. In clear visibility scenarios, divers can rely on visual cues, and while conducting repairs, divers are often focused on their task and may have other safety protocols in place. The use of a buddy line is most crucial when visibility is poor, highlighting the importance of maintaining close proximity to ensure safety and prevent distress during the dive.