For divers following the rule, one third of the gas supply is planned for the outward journey, one third is for the return journey and one third is a safety reserve.

Matthew McConaughey: He is an avid diver as you may have seen in the movie “Fool's Gold” a funny and great movie. If you have not seen it, make a point to watch. Kate Hudson: she became a diver when needing to learn for the above-mentioned film “Fool's Gold”. Jessica Alba: is a PADI Advanced Open Water diver.

Freediving After Scuba Diving Dissolved nitrogen isn't a major concern for casual snorkeling to very shallow depths. But, it is potentially a concern for freedivers who are also scuba divers. Your risk of decompression illness may increase if you freedive after scuba diving.

The "no-stop limit", or "no-decompression limit" (NDL), is the time interval that a diver may theoretically spend at a given depth without having to perform any decompression stops while surfacing.