Nitrogen narcosis symptoms tend to start once a diver reaches a depth of about 100 feet. They don't get worse unless that diver swims deeper. Symptoms start to become more serious at a depth of about 300 feet. Once a diver returns to the water's surface, the symptoms usually go away within a few minutes.

What causes narcosis?

The cause of narcosis is related to the increased solubility of gases in body tissues, as a result of the elevated pressures at depth (Henry's law). Modern theories have suggested that inert gases dissolving in the lipid bilayer of cell membranes cause narcosis.

When does a diver feel narked?

The impact of being narked will generally appear within the first two minutes at a depth. A simple prearranged test should be good enough. You might also want to include a signal to ascend a couple of meters. Be self-aware: Remember the symptoms of nitrogen narcosis.