When you get to the tank, open the door just to feel the weight of it. It is very light. If you close the door while inside the tank, it is completely dark and that may be disorienting. When you get in and before you lie down, open and close the door several times, noticing how it feels different from the other surfaces . If you try to open the door and it doesn’t open, it’s not the door.
Many people have some fear or concern before they use the tank the first time. Fears such as being alone in the dark, drowning, not having enough air, claustrophobia, and others. The fears are usually the thought or the idea that YOU won’t be in control of the situation, but in this situation you are totally in control. You can go in and out of the tank as you please. You can use the tank with the door completely open, you can keep it partially open, or you can close it. There is no particular way to use the tank that is more correct than another. Any way you use it, that is comfortable for you, is correct