The second phrase doesnt connect to the "Me and my friend". So it IS quite a bit nonsensical
Could it be
"My friend and I are in the mid-point of our hike to the waterfall"? That means that you and your friend are at the mid-point either in distance or in the time alloted, for this hike to the waterfall.I think that you are using "between" in a way that its not done in English.