I'm not sure which the largest is, at the moment - I always have questions about accurate length measuring methodology. Accurately measuring a large snake isn't as easy as one would think.
The largest snake in captivity, verified as measured accurately, is Samantha, the retic at the Bronx Zoo. Not sure what her exact length is right now - around 23 feet, a few years ago.
The largest I caught in the wild was 5.45 meters in Ecuador, with a snubbed (bitten off) end of her tail. I have seen
a track of a snake that was at least 6 meters, along a river deeper than the shallow regions where we typically searched.
Renee