True or False: A safety stop is required on both dives if a diver has a 28 minute dive to 24 metres followed by a dive to 18 metres.

A safety stop is a precautionary measure recommended to give divers a chance to off-gas nitrogen after a dive. When considering a scenario where a diver completes a 28-minute dive at 24 meters, followed by a dive at 18 meters, it's essential to understand the factors involved in nitrogen absorption during dives.

In this situation, both dives cause the diver to absorb nitrogen, especially the first deeper dive. A second dive following a deeper dive places the diver at increased risk for decompression sickness, and performing a safety stop after each dive helps mitigate that risk by allowing for the release of excess nitrogen.

The standard practice is to conduct a safety stop at a depth of around 5 meters (15 feet) for about three minutes after both dives, ensuring that the diver reduces the amount of nitrogen that could lead to problems. The requirements for a safety stop apply regardless of the specific depths, provided that the diver has had significant nitrogen exposure on the first dive. Hence, for these two dives, the answer is indeed true: a safety stop is required on both dives.