I wish I could do this.
The reason is because this at lest part of the secret as to how sea lions can hold their breath for an hour underwater, and why I can currently hold my breath for a max of 2 minutes 16 seconds. Sea lions have the same size of lungs as humans and (almost) the same type of blood. I say "almost" because they have quite a bit more hemoglobin, which is the stuff in the blood that carries oxygen. The trick with the spleen is really neat. In humans, the spleen filters and stores extra blood for you. In sea lions, the spleen stores A LOT of extra blood. Right before it dives, a sea lion uses some kind of muscle to constrict the spleen and shoot a lot more blood in the blood stream. Then the sea lion breathes in real deep to make sure that every last hemoglobin is saturated with oxygen. After it submerges, most of the blood is diverted to the most vital areas (brain, muscles to swim, etc.) leaving things like the digestive and reproductive system to resume their functionality on land.
Because of these cool biological tricks, sea lions can comfortably swim around underwater for an hour before needing to take another breath.