We stayed at one of two walk-in sites at Greenwood. The highlights were a spacious camp site, nice bathrooms, little light pollution (we saw the Milky Way!) and hearing screech owls at night.
A couple of really nice things about this campground: You can buy ice ($2), bundles of wood (15 pc @ $5) and as long as you don't need change, it's self serve. The shower house is nice, nothing too fancy but clean. There's also a toilet-only bathroom closer to the walk-ins with a mirror and a baby changing table. It was VERY clean and heated, which was glorious considering it was quite chilly at night. There's also drinking water spigots in several locations which is a big plus and not something you see a lot in most state parks.
The walk-ins are not very far from the little parking lot, so it was easy to carry our gear down to the site. The site itself was HUGE in comparison to the other sites. Also close to a nice little stream.
There were a few big puddles from this summer's torrential rains but surprisingly no mosquitoes to speak of. The only con about this campsite was that it's down the hill from PA 305. It was fine during the night, but traffic started to pick up at daylight. Maybe it would not bother everyone, but it was annoying to be reminded you're right next to the road all day.
Spacious sites with fire pits. Vault toilet and trash. A few minutes down the road from the Bickel Knob fire tower.
As far as camping goes, the loop area is a bit cramped for my taste, but if that doesn't bother you it's fine. Clean bathhouse and convenient outdoor sink for washing up after dinner. Overall one of the best PA parks and well maintained.
I really have to address some of these other reviews, though:
"Water was thick with weeds& lilies but ok nonetheless." Wow! Pitcher plants, sundews and water lilies are not "weeds." They are unique to bog environments and don't grow in other places. The vegetation in the lake is what makes Black Mo black, so picturesque and unlike other PA parks!
"The overall area has nothing to do. And I mean NOTHING. We drove 45 minutes to Altoona to see the famous Horseshoe Curve but there’s literally nothing else around for miles and miles. Not even an ice cream stand, or not one we could find. And, since there’s no cell service, we couldn’t figure out any options either." Like many state parks in this part of the world there is no cell service, so you need to bring a real map (Purple Lizard) and look a few things up on the internet ahead of time. Black Mo is literally ten minutes from Philipsburg where there is surely an ice cream stand, 25 minutes from State College, which has tons of touristy offerings…I could go on but really this is laughable.