The crater visit at night is a very unique experience, but there are risks involved, and the effort and issues you endure to get there may mean that it won't be worth it for some. On the plus side, if conditions are right, you may see some blue lights reflected in the fumes directly above the centre of the crater. After you climb back up to the lip of the crater, there is a reasonable view over the main crater lake and back towards Bali. If you like challenges, you will have ticked off a big one; having climbed down into the crater in the middle of the night and back up again in the morning, wearing a gas mask. On the down side, it is a 4-hour, boring, night-time trip across Bali in the evening (including dinner); having left Legian etc about 6 pm. One hour on the ferry and another hour or more to the Mt Ijen parking lot and a 30-minute wait till everything opens at 12:30. I only endured this because I was going to dive nearby at Permuteran over the next few days. You get back down to the parking lot about 7:30 am, then reverse the trip back across Bali. You won't get much sleep for a day and a half. Back to the actual hike. The walk up the mountain is very long (several kilometres) and very steep for the most part. You need to be fit or you will find it very hard going. The track is extremely dusty when dry, and the fine dust fills the air as there can be hundreds of people are walking up. You really should bring a dust mask, but nobody advises you of this. When you get to the crater lip, you see and smell the sulphur fumes. You need to don the sulphur mask at this point, which makes the steep, 1 km trip into the crater hard work, because it restricts your breathing and makes your heart work harder. Climbing back up is even more difficult. When you get further down the crater, the fumes get thicker, and you have to close your eyes because the fumes sting. When waiting to see the blue lights at the bottom, you can be covered in a dense fog of sulphur fumes for some time until the wind changes, or the fumes reduce. You can't take off your mask,and you can't open your eyes. You can't breakout and escape the fumes, and it is a long haul back up to get out of it. You just sit in the claustrophobic fog and hope that it will clear. You could hear heaps of people coughing and moaning in the fog. I'm guessing they were not wearing masks. BTW, I had to ask for one as we started to head up the track. Nobody had thought to get one for me. I rented a jacket but it was so hot walking up the track, that I had to carry it most of the way up. You do need it though, when the winds blow, and when you are in the crater. The blue lights that show up in the clouds of fumes are nothing as fantastic-looking as photos I have seen on the marketing photos. (I saw almost nothing). The 1 km climb back up to the crate lip, with the gas masks on, is hard work. As soon as the fumes clear a bit, you feel compelled to breathe some free air without the mask, and it may not do any damage for such a short space of time; but it can't be doing you any good either. Even walking back down the dirt track is dangerous. The guide said they have a lot of injuries at this point because people slip on the steep track that is covered in fine dust and tiny pebbles that work like ball bearings under your feet. I slipped on many occasions, even though I was being careful. 'Breakfast' at the bottom was pathetic. It consisted of a bowl of fried bananas and three boiled eggs. No utensils, napkins, salt or pepper or anywhere to wash your hands after the trek we had just been on. Only because I asked, I was led to a hovel of a kitchen where I could use some dishwashing liquid to wash my hands in a dish on the dirt floor. Tea and coffee options were almost zero. I know this is a poor area, but considering the fee paid, it could have been even a little better. I don't know that I could recommend this to most people.