Choose the correct preposition.

1 The hikers set out at/from/off the hostel early in the morning. 2 Be careful you don't fall into/down/through the water!
3 The view from the summit of/at/in the mountain was amazing. 4 We watched the fish swimming over/through/ up the crystal clear water.
5 Rustam ran across/with/between the Kyzylkum Desert for charity.
6 Kunsulu has visited some of the most extreme places for/on/in Earth.​