At sea level, what is the absolute pressure?

At sea level, the absolute pressure is defined as the total pressure exerted by the atmosphere on a given surface. This measurement includes both the atmospheric pressure and any additional pressure from surrounding fluids, such as water. At sea level, the atmospheric pressure is approximately 1013.25 hPa (hectopascals), which is equivalent to about 1 bar or 1 atmosphere (ata).

Thus, at sea level, the total absolute pressure is 1 bar, or 1 ata, making this the correct answer. It's essential for divers to understand absolute pressure because it affects their decompression schedules and the physiological responses to various depths underwater.