Pressure Difference between 70ft and 40ft

[cameron]

I don't know the technical stuff about pressure on one's ears at depth but in my case it feels like there is less pressure the deeper I go. The reason I say this is that once I get below about 30 or 40 feet it is much easier for me to clear my ears. At shallower depths I need to hold my nose to clear my ears but the deeper I go I can clear them just by exhaling through my nose. Doesn't make sense.

How can you be certified and not know the answer to this question? Its a fundamental concept that EVERYONE needs to know before they put on a dive set.

Cam