Why does your body need a SIT time before making repetitive dives?

The need for a surface interval time (SIT) before making repetitive dives is primarily to decrease nitrogen levels in the body. When a diver descends underwater, the pressure increases and causes the body to absorb more nitrogen from the air we breathe. During ascent, if the diver surfaces too quickly or does not allow enough time for nitrogen to safely leave the body, it can form bubbles in tissues and blood, leading to decompression sickness, commonly known as "the bends."

By allowing a proper surface interval, the body has time to off-gas the absorbed nitrogen safely and efficiently. This process helps to prevent nitrogen narcosis and reduces the risk of complications associated with rapid ascents, ensuring safer diving practices. Understanding this physiological need is crucial for maintaining diving safety and health.