Well PBJ is correct in that you should not be held down for a full 90 sec but I was unable to get a breath for at least that cause every time my head surfaced the next wave detonated on me either pushing me under (hence my frined thinking i was under the whole time) before I could get a breath or knocking the one I took out of me. Dawnpatrol has it bout right at around 30 seconds as probably the max hold down. The best bet is to see if you can not hold your breath for 30 seconds but exhale then try not to breath in for 30 seconds (harder than it sounds since breathing is an automatic reflex) as this is the likely outcome in big surf. You would not likely die or get seriously hurt in 10 ft EC surf but you may become a liability to others. Running is good and do lots of push up because broken leashes are common in larger surf and you need to be able to swim in all that soup. Best of luck and I hope we can actually get some 8-10 ft stuff to ride.