1

We went on a local bus to Debark. We then took a scout and a mule man with a mule for a total of about 200 Birr per day, all arranged by the park office. We were very happy with our scout and mule man. Additionally you can take a guide at 120 Birr/day (?).
Plus your park fees, food, camping gear (which we rented in Debark for 150 Birr/day). We did hike to Sankaber (1st camp) on the first day which was quite long! But you can get cars to take you into the park. There are cars that go into the park to pick up tourists to take back to Gonder and they offered us good prices for taking us to Sankaber (since they are already going, empty). We had a fantastic time!! Be prepared that it does get very cold at nights. Enjoy! Thinking about it if I were to repeat this stunning trip I would do more days and include the lowlands. We did 6 days. The couscous we took along was a winner.

2

...and don't forget to tip the scouts, mule man and guides. They earn very little money and tipping sure rewards their great efforts. We gave them 200 Birr each because they were wonderful to us!
And if you go without an agency: don't believe what they tell you at the park office, they do not have their own food, you should bring food for them. Ours had 1 bread per day and were more than happy to accept our invitations to share our food. Even if you don't smoke, take some cigs with you and hand them out at the campsites, the people will love you. I was treated to tea every morning by the chefs of other groups and they would let me try their food - because I was the one with plenty of cigs. Their food was truly delicious!

3

The two of us did a five day trek of Simien mountain, starting from Sankeber and up to the peak of Ras Dashan and back. This trek was absolutely the highlight of our time in Ethiopia, amazing views, amazing animals, lovely people. highly recommended. It cost us 280 USD all inclusive with other 3 independent travellers. We organised a tour with simienmountain@gmail.com through Birhanu. we met others travellers who took the public bus to debark, walked to the park station and arranged themselves without a guide. Scout is mandatory and enough.