The time isn't a constraint at all for experiences JetPunkers. I got in 1:36. Time doesn't need to be a factor in all quizzes, but if you want it to be, I would suggest a time limit of 2 minutes. Nominterpated the quiz.
Once you remember it can’t be countries with a sea coast it becomes just a matter of brute-forcing through landlocked countries. I suggest lowering the time…
Nepal has the Terai plain which is much lower than 100m, and Bhutan has the Manas River basin in the east which is around 100m I believe. Both countries do have a crazy range of altitude within such small area.