[ElDanés]

I thought it would be interesting to read some literature in Spanish, so I found a copy of Heinrich Harrer's book, Seven Years in Tibet, in Spanish: Siete Años en El Tíbet. I would have chosen some Spanish (or Central/South-American) literature, but I couldn't find anything for free, so that's what I have got for now.

I have succeeded reading most of the beginning, but I just can't get a part of a sentence right. This is how it goes: [...] y en Karachi aguardamos que llegue el buque de carga en el que hemos de regresar a Europa.

I have got a feeling of it: they are waiting for a cargo boat to arrive, in which they will return to Europe - but I would like if someone could come up with a better translation. I think it's the subjunctive, llegue, which annoys me. Why exactly is a subjunctive used here? Is it because that it is not sure that the boat will actually arrive? Also, why is the el used like that, in en el que? I can't seem to find it in any pronoun tables.