How do I get "Can't Feel a Thing"?

The Can't Feel a Thing challenge in Caustic Caverns requires you to stand in the acid pools for 30 seconds without entering Fight for your Life mode. When I first got a shield immune to Corrosion damage I thought I cracked the secret. Surprisingly, corrosive-immune shields don't actually protect you from the acid. And at level 38 the acid is still quite painful even in Playthrough 1.

How do I get this challenge? Do I need max level and a crazy shield or is there some trick to it? FWIW I'm a Siren and could conceivably boost up a Turtle Shield with skills and a Class Mod but ideally I'd like to know a way all characters can do this.

I looked into this a little bit (youtube) and it appears that your understanding of the challenge is incorrect: you need to "not go into Last Stand Mode" rather than "not break Shield."

So you need a high level shield and a high high health value. I play as Salvador, and in my case, especially with some skills upgrade, when I activate the Gunzerker skill, my health bar recovers faster than I take damage.

So if you have a health regen skill, activate it right when the shield goes down, and this may delay your death.

( see: http: // www.youtube.com/ watch?v= ZOHBabyZmr8 @ 1:20 )

It is not cumulative, I just tested this. I'm level 26 and can survive about 24 seconds, tried this several times (without falling into fight for life) and didn't pass the challenge.

However you are right that there is a bug. Not 5 minutes after failing to get it normally I got it by standing on a rock barely above the 'waterline'.

My crosshairs show where I was standing in this image. http://imgur.com/vXCVz

It appears that if you are close enough to the acid it still counts you as being in it for the purposes of the challenge even though you're not taking damage. This would explain why some people are getting it when stepping in and out making it look cumulative.