Comment by okmokmz

Yup, technical divers that do extremely deep dives generally use heliox or trimix which can contain 70-90% and 30-45% helium respectively at the surface. The ratios change at depth due to how the various gasses compress, but it's still a much higher concentration of helium than what you'd experience in pretty much any other environment. Unlike carbon dioxide, helium doesn't cause respiratory distress which is why it's a good replacement for nitrogen during deep dives, and also why it's so popular for suicides