This is a Finnish-Swedish folk song, one that I find particularly touching, as I intended to sing it to my then-girlfriend as a Valentine's Day present (but we didn't make it that far, alas). The lyrics, with the English translation below, go as follows:

Vem kan segla förutan vind?
Vem kan ro utan åror?
Vem kan skiljas från vännen sin,
Utan att fälla tåror?

Jag kan segla förutan vind,
Jag kan ro utan åror,
Men ej skiljas från vännen min
Utan att fälla tåror.

And now the English:

Who can sail without the wind?
Who can row without oars?
Who can part from their friend,
Without shedding tears?

I can sail without the wind,
I can row without oars,
But I can't part from my friend
Without shedding tears.

I also found a German translation that is pretty true to the text:

Wer kann segeln ohne Brisen
Wer kann rudern ohne Blatt
Wer kann, ohne Trän' vergießen,
Freund verlassen, den er hatt'?

Ich kann segeln ohne Brisen
Ich kann rudern ohne Blatt
Doch nicht, ohne Trän' vergießen
Freund verlassen, den ich hatt'!

Mouesh was so kind as to find the French lyrics to this song, which, oddly enough, is longer than the original:

Qui peut faire de la voile sans vent?
Qui peut ramer sans rames?
Et qui peut quitter son ami
Sans verser de larmes?

Je peux faire de la voile sans vent
Je peux ramer sans rames
Mais ne peux quitter mon ami
Sans verser de larmes

Qui peut voir un coucher de soleil
sans que la nuit ne tombe?
Et qui peut trouver le sommeil
lorsque le monde s'effondre?

Je peux voir un coucher de soleil
sans que la nuit ne tombe
Mais ne peux trouver le sommeil
lorsque le monde s'effondre

Qui peut croire un instant à l'amour
lorsque deux hommes se battent?
et qui peut oublier pour un jour
le monde et son massacre?

Je peux croire un instant à l'amour
lorsque deux hommes se battent
Mais ne peux oublier pour un jour
le monde et son massacre

And the English translation thereof:

Who can see a sunset
without the night falling?
Who can sleep soundly
when the world is crumbling?

I can see the sunset
without making the night tumble
But I cannot sleep soundly
When the worlds crumble

Who can believe that there is love
when two men are fighting
And who can forget even for a day
the world and its slaughtering.

I can believe that there is love
even when two men are fighting
but cannot ever forget
the world and the slaughtering.

I think the most heart-wrenching version of this song was sung by the late and colossally-great Lee Hazlewood on his album Cowboy in Sweden. But Agnetha Fältskog (of ABBA fame) sings a definitive version of this song, though I feel it isn't nearly as full of the same saudade as the Hazlewood rendition.

Thanks to montecarlo for informing me that this song was a Finnish-Swedish folk song, and not a mere Swedish folk song. Eläköön Suomi! And merci beaucoup to Mouesh for providing the French lyrics and their accompanying translation.