> Also, the Saraswati is not described as having a confluence with the Ganga/Yamuna at Prayag in the Rig Veda - this is a later legend which does not seem to have any basis.
The article is wrong on two counts - (a) that the Saraswati is mythical, and (b) that Prayag is a confluence of 3 rivers - it is a confluence of 2 rivers, the Ganga and the Yamuna.
You do realize that Allahabad (or Prayag) is in the opposite direction to the Arabian Sea, don't you?