Deep Blue Ascent

When the white block appears on the screen you reached the target of your descent. You are pumped with endorphins and happy feelings but the tightness of your lungs is real.

When you are ready then press the fire button (Joystick port 2) to start your ascent journey and use the control to leave as many bubbles behind at the exit point as possible. When you pass a tag on your way up, your dive meter will indicate this at the top of the screen. Keep your focus until you reach the surface again.

Source: https://romwer.itch.io/deepl-blue-ascend-basic-10liner