re: Compare with Jupiter
"The atmosphere is very deep, perhaps comprising the whole planet, and is somewhat like the Sun. It is composed mainly of hydrogen and helium, with small amounts of methane, ammonia, water vapor and other compounds."
source
Apparently these small amounts of other compounds are enough to result in a completely opaque atmosphere. But maybe it only seems that way because light is scattered or absorbed too much. Maybe on a human scale it is transparent. Maybe visibility at any depth is 1000 miles! Does anyone know for sure?