What is the maximum depth of an underwater seat below the waterline as stated in public swimming pool standards?

The correct answer is 20 inches because public swimming pool standards typically stipulate that underwater seats must not exceed this depth. This regulation is in place to ensure safety, as seats that are too deep can pose risks for swimmers, especially for children or less experienced individuals who may struggle to reach the surface. Moreover, the specified depth allows for a comfortable seating area while maintaining sufficient water depth for swimming activities. Adhering to these standards helps pool operators create a safe and enjoyable environment for all users, ensuring that features like underwater seats do not create hazards.