Here is the full list of all 20 Montague's Mount achievements.
You played the gramophone.
You have walked 10 kilometres.
You have located the Old Hermit's shack.
You have found the walking stick which makes your progress easier.
You have walked 1 kilometre.
You have visited 4 of Montague's Mount's beaches.
You have started the old generator.
Solved the Spinner Puzzle.
You have found the 5 MacLaughlin family graves.
You have located the 4 coloured spinners for the bridge puzzle.
You have examined 25 objects.
You have examined 100 objects.
You have lowered the bridge in Pitcairn Point.
You have been playing the game for 1 hour.
You have been playing the game for 2 hours.
You have been playing the games for 3 hours.
You have opened the 4 puzzle gates.
You have located the 22 crosses of St. Brigid of Kildare.
You have completed the candle puzzle in McKenna's dock.
You have found the 5 secret postcards that are hidden around the island.