The Origin of Water is kind of a side mention in runosongs but in my opinion, there could be something very precious in it. I'll start by explaining that "blue cape" can sometimes be a descriptor of a hero.
    Raudan synty ruostehesta Tulen synty taivahasta Vuoresta veden sikiä Vesivitta vaaran poika Vuoen vuoressa maannut Kauan kalliossa levännyt Vesi vanhin veljeksistä Tuli nuorin tyttäristä Vesi on vanhin voitehista Kosken kuohu katsehista Vesi on tullut tunturista Tullut tunturin alaitse Juossut Juortanin joesta Pyhän virran pyörtehestä Pyhän pellon pientaritse Vesiviitta, Väinän poika Suoviitta Kalevan poika Siniviittasen sikiä Vuoresta on sinun sukusi Kalliosta on kasvantosi Ukko vanha Väinämöinen Kuin kiskoi kivestä niinen Vein veti kalliosta Munan solmuun sukaisi |
The origin of iron is from rust The origin of fire is from the sky Water stems from a mountain Water cape, son of a hill Lied in a mountain for a year Rested in a rock for a long time Water is the eldest of brothers Fire is the youngest of daughters Water is the oldest of ointments The foam of rapids the oldest of dews Water came from a fell Came through the bottom of a fell Ran from the river of Jordan From the swirls of the holy stream Through the side of the holy field Water cape, son of Väinä/river Swamp cape, son of Kaleva Stemmed from the blue caped one Your family is from a mountain Your grew up from the rock When old man Väinämöinen Tugged bast/ring finger from a rock Pulled water from a stone Tied an egg |
So uh, how do I begin. Who is "water cape"? Well, he could be the son of Väinämöinen in Väinän poika but as we know, that is more likely to refer to son of a streampool or a river. The title son of Kaleva would set him into the same family as Väinämöinen though, maybe as a brother? Then there is also the view that he is a helper of Väinämöinen, like an armed companion. I have a different theory though.
I think it is entirely possible that "water cape" is Väinämöinen himself. And not only because a runosong from Koillismaa includes the line "water cape Väinämöinen". Here, we see that he came from a mountain; when Påhl Hindrikinpoika Paskoja was accused of witchcraft in court in Ostrobothnia in 1728, he explained that Ilmarinen was a god that people used to worship but Väinämöinen was "something which lived in a mountain". And well, the connection between Väinämöinen and water has long been known and established, so much so that in early research, some tried to present Väinämöinen as a water spirit or even just a corruption of the name of a water goddess.
I also want to focus on the line "tugged bask from a rock". "Tugging bask" (niini) indeed used to be a common phrase. However, while reading the Dictionary of Dialects of Finnish, I found the word niines, meaning the ring finger. Because the runosong records which mention this line do not correctly mark long vowel sounds, the line for tugging bask (niinen) could just as well be tugging the ring finger (niineen). And if we look at the runosongs describing the birth of Väinämöinen or his father, it is said that he released himself from his mother's womb with just his ring finger. Furthermore, there is a theory presented by Kaarle Krohn that one of the candidates for this mother, "Kunotar", would mean the Earth Mother Maatar. Thus, water lying in a mountain and Väinämöinen lying in his mother's womb for a long time could describe the same event.
Of course it leaves the confusing situation that both Väinämöinen and his father Kaleva (possibly a sea giant) are connected to water and are described having been born in this same way. But at least the idea of water being the eldest of elements could explain why Väinämöinen is always seen to be the eldest out of his brothers. (Even older than the original creator god.)
Usual explanations, the river Jordan and holy stream are the river of the Underworld, just Christianized, and the holy field is the field of Osmo who might or might not actually be Kaleva, huh.