Boromir's search for Imladris

[Tuor in Gondolin]

I agree with Boromir probably going up the Mitheithel, once he lost
his horse. Surely tales of Earnur's victory at Fornost (even though
a thousand years ago) was known and was an epic tale sung during
festive occasions in Gondor, and as an exciting battle, enjoyed especially
by Boromir. And in that battle the important role of both Cirdan and
Elrond, and the general direction from which their forces came, would
be known, at least in so far as it was east of the Weather Hills and
near the Misty Mountains, and so a natural aiming point for him would
be the area of the intersection of the East Road and the Metheithel.
Once on foot journeying by the riverside would be shorter and quicker
then going up to Bree and then east (although with less chance of
aid from travelers or others).