Just reading and writing about blood loss has made me feel a little lightheaded, and then I realized where I'd seen the term hypoxia.
Hypoxia can occur at high altitudes, especially if scuba diving at high altitudes, because the air has less pressure than at sea level and you inhale less oxygen.(1)
To prevent hypoxia while scuba diving at high altitudes (which could kill you), you should take a few days to acclimatize yourself to thinner air, make sure you don't over-exert yourself underwater, catch your breath regularly, and rise to the survace slowly.(1)