What is a requirement for performing dives with longer than 120 minutes of in-water decompression?

When performing dives that exceed 120 minutes of in-water decompression, the requirement for using a bell is crucial for safety and effective management of the dive. A bell, which is a diving chamber, allows divers to make decompression stops in a controlled environment. This is important because it provides an air supply and shelter from the surrounding water, ensuring divers can complete their decompression safely while minimizing exposure to the potentially harmful effects of long-duration dives, such as nitrogen narcosis and decompression sickness.

Using a bell enhances the ability to safely manage divers during prolonged decompression periods. It can facilitate easier communication with surface support, allowing for a more organized and efficient decompression process. The controlled environment of a bell also helps to monitor divers’ conditions, since they can be assessed for any signs of distress or need for medical assistance while still in the water.

The other options, although important in different contexts, do not specifically address the critical aspect of performing long dives with extended in-water decompression. The use of a bell is essential to ensure the safety and well-being of divers under these circumstances.