In my opinion, the question, which I had seen so much , Why was it difficult for them to down the crater?isn't the correct one. It should have been;Why it was difficult to go down the chimney
As they didn't face any difficulties while they were descening the crater as it was mentioed in the text
and concering the last answer , it was getting narrower and darker ; this was in th chimney
You can return to the text and make sure of what I had mentioned
Am I right or wrong? please answer me my dear collegues ,