Why don't they make longer snorkels so that people could dive deeper without scuba gear?

Answer 1

Imagine a tall hollow tube, 1 inch square in cross section, and closed at the bottom. Fill the tube to a depth of 1 foot with water. The weight of a column of water 1 foot deep, bearing down on 1 square inch is approximately 1/2 a pound. Add another foot of water in the hollow tube, and the weight at the bottom is doubled - about 1 pound. Keep increasing the depth of water in the column, and the weight bearing down on the 1 square inch bottom increases at the rate of 1/2 pound per foot of depth.

Pressure is defined as Force divided by Area. A 10 foot column of water produces a pressure of roughly 5 pounds per square inch at its bottom. Also, pressure is omnidirectional. That is, pressure at any given depth pushes equally in all directions.

Now suppose you stand at the bottom of a swimming pool and try to breathe through a long snorkel. Let's suppose your breathing diaphragm (the sheet of muscle at the bottom of your chest cavity) is 4 feet below the surface of the pool. The water pressure at the level of your diaphragm 4 feet underwater is 2 pounds per square inch. Through the snorkel, your lungs are connected to the air above the water, and the weight of water bearing down on you by gravity is trying to squeeze the air out of your lungs.

How much total force is this? Suppose your diaphragm measures about 4 inches by 10 inches, so it has an area of 40 square inches. Then 2 pounds per square inch of water pressure applied to 40 square inches of diaphragm equals 80 pounds of force. Drawing breath against 80 pounds of force is extremely difficult! Doing it for more than a few short breaths is definitely impossible.