So I got the idea for this thread from Reddit and it did make me think what was the most difficult season/s? Some of the early ones have to be up there. Namely Season 5 for sure. The sheer distance covered and how each country visited was so different from the others. We had the frigid Russian climate, The heat of Egypt and UAE, The wildlife of Tanzania and so on and so forth.
Season 6 I reckon was very difficult looking back with the number of difficult legs in there, Hungary I actually consider to be one of those difficult legs same with Ethiopia, China II has to be considered one of the hardest legs in TAR history in my opinion.