Which of the following conditions is considered a significant hazard during diving?

Exceeding the maximum bottom time is a significant hazard during diving because it directly relates to the risk of decompression sickness (DCS). Each dive has a recommended time limit based on depth to ensure that divers can safely ascend without allowing excess nitrogen to accumulate in their bodies. If divers exceed this limit, they increase the likelihood of developing DCS, which can cause serious injury or even be life-threatening.

While having no safety divers present is a concern and could affect safety, the immediate risk posed by exceeding maximum bottom time is more critical in terms of physiological effects. Conversely, all divers being certified does not inherently imply an increased hazard, as certification indicates they have completed necessary training and understand safety protocols. Additionally, a current of less than 1 knot is generally considered manageable and not a significant hazard, especially for experienced divers.