I never dived any deeper then 36 meters, and always made sure that I did my safety stops. Before diving you make sure your equipment is checked, during the dive to check your dive computer on a regular base, because you want to know how deep you are, how much air you have left, and if you're not ascending or descending to fast. If you follow the rules and do that what you have learned, diving should be safe.
Panic will get you killed. I remember one dive in The Netherlands. The water was far from bright when you looked at the surface, but after descending it went to a dark greenish, with a visibility of less then a meter. In a few minutes I lost my buddy, and had to held my computer close by to see how deep I was. It really felt like maybe 7 or 8 meters, but it appeared to be 20 meters. I knew that certain areas on this diving spot were as deep as 80 meters, so I decided to slowly ascent. But you have to make sure what's up and what's down, so you just look at the bubbles. They always go up, so you know which way to go.
