What specific data forms the foundation of most recreational dive tables?

The foundation of most recreational dive tables is based on U.S. Navy dive data. This data is derived from extensive research and testing that the Navy conducted on the effects of pressure on the human body and how to mitigate decompression sickness. The U.S. Navy's decompression tables were developed using empirical observations from deep dives and experimental results, which established the safe limits for both ascent rates and bottom times at various depths.

These tables are widely used in recreational diving because they provide a standardized approach, helping divers to plan their dives and make safe ascents. While other types of dive data exist, such as those from the International diving standards and commercial diving data, the U.S. Navy's approach remains the most widely recognized and used in recreational settings. This is due to its rigorous validation and widespread acceptance in the scuba diving community.