What are some underwater hazards divers might face?

Underwater hazards like entanglements, strong currents, and potentially dangerous marine life are significant concerns for divers. Entanglements can occur when divers become caught in fishing lines, nets, or other debris, which can restrict movement and pose a danger to their safety. Strong currents can greatly affect a diver's ability to navigate and return to the surface safely, requiring divers to be skilled in managing their buoyancy and understanding how to work with the current rather than against it. Additionally, encounters with marine life, such as jellyfish or aggressive species, can also present risks, requiring divers to be educated about marine behaviors and safety precautions.

In contrast, the other options present scenarios that are generally not considered hazards for divers. Bright sunlight and calm waters are typically favorable conditions for diving. Lack of visibility and communication may pose some challenges, but they do not encompass the fundamental hazards divers actively prepare for. Excessive buoyancy and high temperatures can affect comfort but are not threats in the same way as entanglements, currents, and hazardous marine life. Thus, focusing on the hazards that directly threaten diver safety is crucial in the context of underwater diving.