Saturation Divers

Have you heard of saturated divers? They are basically like astronauts but they go veeeerry deep underwater. They also board a capsule, it will gradually match the ambient pressure of the depth they're going to work on while they breath trimix, a mixture of some vewy few nitrogen,oxygen and more helium. Apparently human body exposed underwater with such great pressure, theyre blood will eventually be saturated by nitrogen, so they need some vewy few oxygen and some helium in theyre tanks, helium counter acts the narcotic effect of oxygen and nitrogen and it eases breathing i think?, and reduced oxygen flow since oxygen becomes toxic in high pressure environment but they still need some. Well i think you know what happens to people inhaling helium in balloons, they will have this funny chipmunk voice, well imagine inhaling a load of those in a month, it makes communication harder for them. They also dont go back to normal pressure world after a day to prevent decompression sickness.
They are working for oil rig companies, they do like advanced oil pipe plumbing down there. They might also been exposed to big scary lookin fishes and sharks down there.
But hey they do get alota salary 30,000$ to 45,000$ per month making that job one of the well paid jobs in the world.
But also one of most dangerous job tho.
If they resurfaced or abruptly depressurised, theyre blood will be fizzlin like a shaken coke.
The more you know....