Here is the full list of all 10 Dear Esther: Landmark Edition achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Uncover 4 urns
Trigger all director's commentary
Trigger all voice over points
Walk 5000 steps
Finish Chapter 'The Beacon'
Drown Once
Finish Chapter 'The Caves'
Finish Chapter 'The Buoy'
Finish Chapter 'The Lighthouse'
Die from falling off a cliff once