Narco subs are mostly/entirely submerged to reduce visibility, but they almost all still operate at the surface

It's not a submarine and I wish news outlets would stop saying "narco sub". It's a surface vessel designed to have only a very small part above water. Building an actual submarine capable of submerged travel for lengthy periods is quite difficult.

The wavelengths used in satelite communication are entirely absorbed by water. I think the sub would have to surface to use the antenna.

Semi-submersible wild be a more accurate description. Most of the boat is under water, usually only an inch or so down so it’s hard to see from a boat.