After sleeping on it I know exactly what happened.
1, The nether server crashed at some point. Somehow this ended up with a bizzarre pairing in the nether from the town portal i.e. Three portals in a very large open area with a ghast and zombie pigs.
2, One of the three portals was elevated in the air for some reason. Someone in the guild must know about this, because there was a makeshift cobblestone platform and 1x set of stairs going down. Either it was on the floor and they dug all the netherrock away leaving it a very dangerous place to port in, or the portal generated in the air somehow. Hopefully one day someone can fill in the blanks here.
3, I did not realise, or I forgot, that ghast fireballs = fire. Therefore explaining why a portal mysteriously "closed" behind us the first time we ported into said large chasm. The bugger was firing at us from the second we arrived.
4, After porting in and dying and having that bloody ghast fire at us when we port in, we managed to accidentally deactivate all the portals. Bad because we couldn't get our stuff. Good because everyone else is now safe.