I cannot find any minimum training depths listed for GUE Tech 2. Most agencies list minimum and maximum training depths. I see max depths listed in GUE standards. Not that there is anything wrong with no minimum. My personal belief is that the only real benefit of depth when doing experience dives is for the student to experience how fast gas goes. And, maybe seeing milestone numbers for a confidence boost while being totally clear-headed. For the instructor the benefit is assessing student comfort with depth. While there is no substitute for the real thing, almost every other aspect of a trimix dive can be simulated. I had to postpone teaching a PSAI Trimix 2 class due to conditions at depth being unsafe. Would it be possible to teach a Tech 2 class above 170 feet of actual depth in GUE standards? Just curious. As a GUE student, my classes did Tech 1 diving at 150 feet and Tech 2 at 230 feet IIRC. But, all things being equal, carrying 3 bottles, doing rotations, doing Tech 2 speed changes, could a Tech 2 be done at 130 to 170?