Board Thread:Questions and Answers/@comment-26159148-20150301173320/@comment-3253026-20150301191600

High rank and G rank quests place you in a random spot on the map, the secret area is one of them. It's inaccessible otherwise, think a giant cliff that you can't climb back up. So you either have to get lucky and be placed there randomly or get the felyne explorer skill from the kitchen and be placed there 100% if your quest places you randomly.