What is the maximum allowable depth for a scuba dive using cylinders less than 100 scf?

The maximum allowable depth for a scuba dive using cylinders less than 100 cubic feet (scf) is established to ensure diver safety and to manage the risks associated with nitrogen absorption and potential decompression sickness. When using smaller cylinders, divers are limited to a depth of 100 feet of seawater (fsw) due to the associated factors like gas consumption, especially when considering the reserve air needed for ascending safely from deeper depths.

Diving deeper than this limit would increase the risk of running out of breathable air during the dive, thereby compromising the diver's ability to safely return to the surface. Additionally, there might be considerations regarding how quickly nitrogen builds up in the body, which becomes more critical at greater depths and dive durations.

The other options suggest deeper depths which exceed the safety parameters outlined for smaller tanks, where a more conservative approach is warranted to prioritize diver safety and effective air management.