Narcosis
It is very possible to get narcosis while freediving.
Narcosis in constant weight will happen in the following conditions:
- Dives to more than 65m (> 70m if you are a scuba diver who is very used to narcosis)
- You must also be cold, in cold water
- The water must be very dark
- You have high CO2 (i.e. you didn't overventilate)
If all 4 of those are satisfied, you will almost certainly get narcosis during the early part of the ascent. If you dive more than 70m in cold dark water (and being cold), the narcosis will be very noticeable. More than 80m, the narcosis will be so severe that it is dangerous-- you can even forget to keep kicking. More than 85m, the narcosis is very dangerous. On very deep dives you can also get narcosis during the last part of the descent.
The signs or freediving narcosis are not the same as scuba narcosis, but similar. Everything seems 'wavy', everything sounds distant, you can't think clearly, you feel a buzzing all over your body, feeling 'drunk', can't concentrate on kicking, confusion, fuzzy vision, fear, dizziness.
In warm, clear water, there is almost no narcosis during constant weight. In warm clear water, I have heard that you must do a dive to 100+m on a sled to experience narcosis.
Eric Fattah
BC, Canada