Can you complete the game without death donar because when you do the Death sonar achievement and carry on you still don't get death sonar?

you have to not get the death sonar at the beginning, so on the vents level (I think its that one) don't rescue the dolphins and complete the level, then play through to dark water and you get the achievement.

You won't get the achievement if you have got the death sonar, even if you haven't used it.