Related trivia: Technical SCUBA divers use a helium-oxygen breathing mixture for deep dives. In cold waters, most will carry a small cylinder of air or argon for inflating their drysuit, because a heliox-filled drysuit has significantly less insulative value.
One time the gas supplier accidentally gave us helium in the argon supply cylinder and so my dive buddy ended up with a drysuit inflation tank full of helium. He couldn't figure out why he was freezing his ass off during the dive until he returned to the dive shop and checked that tank with a helium analyzer.
