Decompression sickness
If a diver gets decompression sickness it can be treated by putting the diver in a decompression chamber, and increasing the pressure to squeeze the bubbles to a smaller size where they do less harm, and by giving the diver pure oxygen to breathe, which helps to get the bubbles to dissolve again. The oxygen also helps to stop more damage to the body by the bubbles which have blocked blood vessels, as there is more oxygen in the blood to keep the parts alive which have less blood supply because of the blockages.