See, here is to explain that in today's time, the excess of opencast mines is very high. Because opencast mines are being opened everywhere. We know that opencast mines are more profitable according to underground mines. Because opencast mines have less risk and production is higher. That's why underground mines are almost closing. Its main reason is that the danger is very high in underground mines. And the production is very rare. Underground mines are prone to fire, gas (methane), carbon mono-oxides, and much more gas that harm humans. That's why even today opencast mines are more profitable.
But we cannot choose it because you get mines only after you pass the exam, and the biggest thing is to pass the gas testing exam to work in underground mines. Both mines are good in their places