The first question is how big. The answer, 4 wheel drive big. As the photograph shows he was also looking right at us, knew exactly where we were.
Now, I was not sharing space with him no matter how the image looks. I use a long lens. Obviously I was close enough to get all the details though.

A size guess is maybe 11 feet (3.4 m).
Add a little more fun to the story, on either side of him was another just as big. They were all getting warm after a chilly night.
This article is the first of several containing photographs of ‘the big guys’. This is the time of year when they are out moving around and getting warm. A walk along a dike the other day brought us to at least a dozen along just that path.
Most all either ignored us or slipped away.
Wow! Amazing.
One of many that day. Still working on some other interesting shots. An apex predator, not pretty, and sneaky… but fascinating also 🙂
He is huge! Looks very peaceful while napping. I wouldn’t dare to take his picture even with long lens 🙂
Yeah, pretty big. There is no Alligator hunting in these marshes so the only predator they have is each other. They grow big around there. BTW, he was not the biggest by far.