Chilling on the surface in Smitswinkel Bay

Nitrogen narcosis

On a dive this past weekend to the SAS Good Hope in Smitswinkel Bay I had the pleasure of experiencing nitrogen narcosis for the first time, and it wasn’t pleasant. I was diving on Nitrox 34%, doing my 70th dive, and was with Tony, Kate, Tami and Justin. The surface conditions were magnificent, I was feeling well rested and looking forward to another visit to the Smitswinkel Bay wrecks. The visibility was not great – water was very green, rather cold (14 degrees) and we could see maybe four metres maximum.

Dodgy green viz on the SAS Good Hope
Dodgy green viz on the SAS Good Hope

Tony and Kate were coming down very slowly because her ears were hurting. They had to ascend for a while and come back down, so I continued my descent on the shot line with Tami and Justin. We were – I am pretty sure – going quite slowly, because the skipperĀ had let out a lot of line and large portions of it were almost horizontal in the water. At about 25 metres I started to have a hot, lightheaded feeling that felt a bit like pins and needles in my scalp. It felt like my field of vision was narrowing (even more than it usually does on deep dives), and that I was about to black out. I couldn’t think properly – didn’t feel good.

The solution for most diving problems seems to be “ascend a few metres and wait for the effects to dissipate”, and that was all I could think to do. I grabbed the line – took several tries – and went up about three metres, hoping like heck that the feeling would pass. My intention had been to descend to the deck, which is at about 30 metres, and explore there, but Tami and Justin, who were on air, rocketed down to the sand far below. I could see Tami spreadeagled like a starfish metres below me, and wasn’t even sure she was conscious (I have a vivid imagination). If she was feeling the same way I was, there was no way I could go and fetch her and slap some sense into her until my head cleared. It was at this point that I started to feel quite strong anxiety, also a symptom of narcosis.

Fortunately after a few seconds (I think – hard to tell how much time passed) I started to feel better, and resumed my slow descent. This time I got past 25 metres without feeling strange, and was able to go all the way to 30 metres comfortably. I had reached the deck of the ship, but was reluctant to go further in case I started feeling odd again. I was also very cognisant of not exceeding the maximum depth limit for the Nitrox mix I was using (34% allows you to go to a maximum depth of 31 metres and an ABSOLUTE maximum of 37 metres). Then I tried desperately to get the attention of my two buddies to tell them to come up a bit so that our dive time would not be too short and so that they’d have enough air to enjoy it!

After the dive I floated on the surface with Kate and Justin, laughing like a drain. Probably unrelated to the narcosis and more just relief that everyone had surfaced safely… But Justin said he wanted some of whatever I was breathing!

Chilling on the surface in Smitswinkel Bay
Chilling on the surface in Smitswinkel Bay, looking like a spaceman

While I didn’t particularly enjoy the experience of being narced (if it was indeed that and not a mild case of oxygen toxicity – the initial symptoms are similar), I am glad that I now know what it feels like, and that the recommended solution – ascending a couple of metres – works, and fast. I’m also relieved that my brain still worked enough to implement that solution. This wasn’t my first deep dive, it wasn’t the deepest dive I’ve ever done, I am not a new diver, and the descent wasn’t ridiculously fast… So I guess this can happen at any time. The causes don’t seem to be terribly well understood. I’ll chalk it up to experience.

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Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

13 thoughts on “Nitrogen narcosis”

  1. dives like this make the ”stay with your buddy” part of the dive briefing, sadly often ignored, but clearly important.

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