What is a potential area of danger near a pool environment?

In the context of pool safety, shadows cast by structures can create areas of danger because they may obscure visibility and make it difficult for lifeguards and swimmers to identify potential hazards. When the sun casts shadows, it can lead to decreased awareness of the swimming environment and affect a swimmer's ability to see obstacles. Additionally, shadows may indicate a drop in temperature in those areas, which can influence a swimmer’s comfort level and behavior. Understanding the implications of visibility and environmental conditions is crucial for maintaining safety in a pool environment.

The other options, while relevant to pool safety, do not present the same level of potential danger. High diving boards can definitely be risky, but they're typically monitored and managed with specific rules. Designated swim lanes are established for swimmer safety and organization, while safety signage is meant to inform and protect swimmers, presenting no inherent danger.