The Seven Sisters (also goes by the Norwegian names of "De Sju Søstre" or "De Syv Søstre" or "De Sju Systre" or "De Syv Systre") are definitely the most famous waterfalls in the Geiranger Fjord (Geirangerfjorden). From what we could tell, it consists of several columns of water, which is how this waterfall got its name (as someone envisioned there were seven of these columns). I don't think we were able to count seven of them, but perhaps that all depends on the amount of snowmelt or rain. Besides, I understand that it's rare to actually see the stream segment into seven waterfalls.The Seven Sisters are actually directly across from another waterfall called Friaren. There's a story about these falls, but I'll defer you to the Friaren page for it.
As alluded to earlier in the page, we noticed that there are many different Norwegian spellings of the Seven Sisters. I attribute this to the fact that the word "sju" meaning "7" could also be the word "syv", which was also "7" in the older Norwegian tongue. I learned this after a hotel clerk (who was trying to test my Norwegian upon hearing that I was trying to learn it) mentioned our room number was "syv" and not "sju," and then went on to give me that explanation that "sju" and "syv" are the same thing. Likewise, the plural form for the word "sister" which is "søstre" could also be "systre." So given two different ways of saying two different words, that's how we got four permutations of the same "Seven Sisters." But regardless of how you see this waterfall referred to, our topo map indicated that the more formal name for this waterfall is Knivsflafossen (Knivsflåfossen; "KNIVS-floh-foss-un").
Naturally with this waterfall being one of the highlights of a Geiranger Fjord Tourist Cruise, you're practically guaranteed to see it once you crowd into such a tour. However, there's also a less touristy ferry that goes from Hellesylt to Geiranger or vice versa where the falls might also be seen (though we didn't do it). You'll also typically see Ljosurfossen, Gjerdefossen, Bringefossen, Grinddalsfossen, and the aforementioned Friaren as well as many others on the waters of the fjord. Any wonder why it's so popular and famous?