Since 1997
Diving After Flying
by DAN Medical Team on March 1st, 2016

​It takes most tourists 24 hours to get to our resorts here in Thailand. I notice that many tourists begin diving immediately when they arrive and often start drinking quite a bit of alcohol. Aren't they at greater risk for decompression sickness after their long flight if they begin diving right after they arrive? Shouldn't they wait one day before they begin diving?
​Mild dehydration can occur on long flights, especially when travelers cross several time zones; alcohol consumption can also contribute to dehydration. Generally speaking, dehydration is thought to predispose a diver to decompression illness because the washout of inert gas (nitrogen, in diving) is less effective in a dehydrated individual.

If there were a relationship between diving after flying and DCI, we would expect to see a great deal of decompression illness on the very first day of diving -- indeed, some data suggests that there are more accidents on the first day of a planned multiday dive trip. Of the 88 cases reviewed from the Caribbean for 1994, 33 -- or 37.5 percent -- occurred on the first day. The remainder occurred on days two through seven. Given that there are thousands of tourist divers who fly to Caribbean and Pacific dive sites, these numbers are far too small to establish a cause and effect.

([This paragraph has been revised following valuable input from a DAN Member - under Comments]: The evidence of an increased incidence of DCI on the first day of a dive trip is not sufficient to recommend a 24-hour waiting period before diving after flying. However, it does indeed support the advice of starting off much more gradually with fewer, shallower, more conservative dives right in the beginning, especially whenever there has been significant travel; the potential for more dehydration; a delay since diving previously; where the use of unfamiliar, rented gear is involved; if there is a lack of familiarity with the dive-site; etc. Taking it slow also gives divers an opportunity to rest and rehydrate, adjust to a new climate and time zone, and acquaint them selves with the new / rented dive equipment.


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2 Comments

Peter Southwood - March 24th, 2016 at 5:28 AM
Why not recommend good hydration and a low deco-stress dive to checkout rented equipment as first dive. 24 hours after flying seems a bit extreme for something which has no convincing evidence one way or the other. Excessively conservative recommendations will get DAN a reputation for excessive conservatism, and people will stop taking the recommendations seriously.
DAN Medical Team - April 6th, 2016 at 12:47 AM
Thank you for pointing that out, Peter.

Indeed, DAN is careful not to impose restrictions in lieu of actual evidence. We have revised the wording to make this even clearer.

Current evidence does support an elevated risk of DCI following initial dives on a dive expedition. There are many possible reasons for this. As such, your recommendation of doing an initial conservative dive is very sensible, especially if it has been a while since the individual's last dive; when gear is being rented and is untested / unfamiliar; when the dive-site is unfamiliar; and if there has been significant travel with potential dehydration, etc.

Thanks for the valuable comments!
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