Translation of frontier in German

Then we did a boat trip which started somewhere in the delta and ended somewhere else in the delta. Each couple received a boat and an elderly lady had to row. I did not feel comfortable with that.
After ten minutes and after drinking a bottle of water we returned to our place. It was already three in the morning. We were unhappy to miss a great party, but our physical conditions were bad.
One hour later, at sun set, we overflew the amazing Misti volcano which is located right above Arequipa. The mountain had a golden glow and its view was breathtaking.