If you see survey markers go for the lower number and the lower letter (ie, choose to follow from station 20 to station 1, not v/v; then look for the A or B survey rather than the D or BB survey).
Water sometimes flows into a cave and sometimes flows out...not reliable unless you noted it first (probably not in your disaster scenario). If you came into the cave in a wet passage, you probably were low since water levels fall.
BTW, why is it that we always term them 'cave entrances' and never 'cave exits'?
Anyway, that's the reason I always cave with a 4-mile long ball of string and two bags of bread crumbs.