As I was driving in to work today, it occurred to me that in his autobiographical reminiscences, Dr. John H. Watson spoke of “…an experience of women spanning …three continents.”
But what three continents?
Europe, certainly, 'cause that’s where England (and Mary Morstan) are.
And we know he was in Afghanistan, which is in Asia, and so I guess we could, if we were mischievous, postulate an alliance with some wild Afghan hill-maiden.
But what was the third continent?
Oh - so you’re not talking about Doctor Who?..never mind…
I always guessed North America, but that’s because I am from the United States and thus incredibly self-centered.
Well if he served with the 66th Foot he would have been based in India pre-Afghanistan.
That means at some point he would have shipped out from England to there (and back again) which would have happened by sea.
That would have meant either a trip through Egypt (once the Suez canal had opened) or round the Cape. Either way, as a young Officer it seems inconceivable that he would not, in the words of Edmund Blackadder, have spent some time “learning how to say ‘do you do it doggy-doggy’ in swahili.”
So basically, “Africa” is almost certainly the answer to your question.
This question has produced many thousands of pages of speculation by Sherlockian scholars. Of course, the entire point of Sherlockian scholarship is to refute what everybody has said before and come up with a new theory of your own.
Europe is a given, since England is part of Europe.
Asia is possible, but some people object since the war had already started when Watson landed in Bombay and he rushed right to the battlefield, got wounded, and was an invalid in a hospital for several months before coming home, giving him little opportunity for dalliance. No Victorian gentleman would make a public reference to encounters with prostitutes and those would hardly be the sort of experience of women that was being referred to in the first place, since the quote comes the first time Watson sets eyes on his future wife.
Africa is unlikely because of the same logic.
Australia is a much better bet. In The Sign of the Four, Watson says specifically that he had “seen something of the sort on the side of a hill near Ballarat,” presumably meaning he had watched the prospectors dig there. So he has been to Australia. The problem is, when? There’s no evidence that he left England after returning from the war and the usual date for his birth, 1854, leaves no time for a medical degree before going to war in 1878. Either he was a precocious boy or he was older than usually postulated (though there is zero evidence of a birth date) or else he had traveled in the 1880s.
If he did travel without mentioning it, then any continent is a possibility. This hole is large enough to drive any number of lorries through.
Two marriages are specifically mentioned in the Canon, both after this quote, but the laxness of the dating of the stories by Doyle, the world’s laziest hack, who didn’t even bother rereading the first half of stories when writing the second half, let alone go back and try to avoid errors, allows other marriages to be reasonably inferred. I’ve seen articles with up to six marriages. If the good doctor had been married multiple times then his experience of women would be very real, whatever continent he found them on.
With no real evidence and the entire world open to speculation in a make-your-own-rules game, there can never be an answer to this question. Have fun with it.
What better place to meet a nurse? “Several months” gives plenty of time for a relationship to flower and then, regrettably, wither. And a nurse would be of his own social class, unlike an Afghan hill-maiden. 
I like your point about Australia.
If I remember correctly, the two marriages are inferred from a mention of “… my own sad bereavement” in a story dating after the Doctor’s marriage to Mary M.
But one commentator pointed out that that could just as well apply to the loss of a beloved child, and that’s the interpretation I like; I believe in one marriage and one marriage only, to the sensitive and compassionate Mary Morstan, whom he amused with garbled stories about tiger-cubs.
Back then, to travel between Britain and India, you went through the Suez Canal. If you get off the ship for some sight-seeing at the Suez Canal (as I did with myt family about 50 years ago), you go to the African side, in Port Said or Suez. It’s only just in Africa, but it’s definitely Africa. If the ship stayed there long enough, you might even go on an excursion further into Africa, e.g., to Cairo or the Pyramids.
Could he have spent his invalid time in Suez or Port Said?
More than one commentator certainly. All part of the whatever you say I will refute syndrome.
I can’t buy it myself. The evidence is total that Watson moved back in with Holmes after the Return, that no wife or marriage is mentioned in cases covering the next eight years, and that the break in continuity in 1902 for a wife is something entirely new. That Watson abandoned his wife for eight years after the death of a (totally unmentioned) child is a theory beneath contempt. It’s just not done, doncha know, pip pip.
More plausible are theories that they merely separated, or that her health or mind broke and she had to be institutionalized. Still doesn’t explain eight years of silence.
As for nurses, here’s the original paragraph:
Except for a bit of time basking on the veranda, Watson was bedridden while at the hospital. At a military hospital. In Afghanistan (or possibly over the border in India, depending whose jurisdiction Peshawar fell under in those days.) In 1880. All the nurses would have been men, remember. (Florence Nightingale comes earlier, but I’d need to see more evidence of female nurses in an Army field hospital on the Indian border at the time.) Trying to fit a romance with a female in there is pushing history till it breaks.
The troopship is no better. Few women would be on a troopship.
Postulating romance while going to Afghanistan suffers from all the problems I’ve already mentioned. Officers might well have gone ashore in port, true, but time for romancing would be limited, and again, Watson could not be comparing his experiences with prostitutes with meeting his wife. Remember also that the war had already broken out before Watson could get to his regiment. (“The regiment was stationed in India at the time, and before I could join it, the second Afghan war had broken out.”) Although that wording allows the technical possibility that the war could have broken out in the days between Watson’s leaving Africa and arriving in India, that’s not a likely explanation. It stretches credulity that Watson would have had a month of shore time along the way to meet women.
Watson’s military days seem to have been all-male affairs, so to speak. We have to look elsewhere for his experiences with romance.
I always maintained that the actual quote should have been “spanning 3 countries” but the sloppy editorial work was to blame for the word “continent” being used.
If we then postulate a medical school romance in Scotland,a romance in either Ireland or perhaps France during pre-army travels and a wife in England we have 3 countries.
I don’t see how you can get that out of the original.
Extends over many nations and three separate countries? No. That’s torturing the language beyond all bounds. Not even Watson’s notoriously bad handwriting can explain that.
(And don’t forget the phrasing of “separate” continents. That seems to leave out Asia, which isn’t separate from Europe. 
)
With women, at least. This is a product of the British public school system who spent much of his adult life shacked up with another man, after all.
Usually they last a few seasons, but since he doesn’t age he can’t really hang on very long.
Oh I see. This question is doomed the way it is titled.
Just sitting here at work spitballin’ 
So, Europe, Asia and the Indian subcontinent. Ha! got you.