Originally Posted by capta
The reality is that the standard length of a snorkel is the max a normal human can breath underwater.
Even a 1' extension will not work. No amount of valves will change that without pressurizing the air. Snorkels are pretty uniform in length for a reason. There are no extra long snorkels available for the macho man (or woman).
Naaaaaaaw! Not true! Maybe you're weeny lungs.
The reason they're the standard length they are is because the human head is a pretty standard size and that's all the length you need to clear the surface.
Even if it were true that 1 foot of 1" tube was all you could do, you could calculate how much resistance that is, and increase your diameter (ie lower the resistance) in order to compensate for your increased length.