Which of the following is a dangerous situation while diving?

Diving alone without equipment checks presents a dangerous situation because it significantly increases the risk of encountering problems underwater without the immediate support of a companion. Diving relies heavily on both equipment function and buddy support; both factors are crucial for safety. Without performing adequate equipment checks, a diver may overlook critical issues such as a malfunctioning regulator or a leaking BCD. Being alone means that if an emergency arises, the diver would not have any assistance in resolving the situation, potentially leading to serious consequences.

In contrast, remaining calm during an emergency is a vital skill that can help a diver manage unexpected situations more effectively. Following your buddy closely, while it could complicate certain situations if done excessively, generally fosters communication and support. Lastly, surface diving to recalibrate would typically involve checks or adjustments to buoyancy and is a normal practice when executed properly, enhancing safety rather than compromising it.