Ok. With 7894 hours and using a Galileo Sol, I bought this myself. Some friends dive with me and I like the old way of keeping tabs on my buddy. I can check on them and they dont even know. Ie. No Tables in my hands. They know me and how I dive. They come for help on mixes but want to do the reps. I know the feeling! So, old school or not it is a real app. And asking for altitude diving is a good one. I dive at over 6700 on some occasions, higher before but not offten. Add the altitude and you have an app for the masses. Slider for time needs to be replaced with number entry for time... K PS; no need to take the phone in the water! Though a dry bag is a good idea on the boat or shore.