There are usually a good number of American alligators, locally called gators, at Brazos Bend State Park in Texas. Most lie in the water, as in the featured image. A few warm up in the sun on the banks of the lakes/swamp, sometimes just feet away from the visitor path. They are pretty docile, and probably well fed, but it is well to be wary.
This proximity does give the opportunity for close-ups of those craggy reptilian bodies.
I think that the open mouth was just a convenient resting position, and not the anticipation of a good snack!
These animals can grow to 4 metres long and weigh over 400 kg.