I'm lvl 13, unarmed specced, I went to a cave south-west of the Ranger Station near Novac.
And what's inside?
4 deathclaws.
I hadn't saved on a real save for a while so I panicked, died and had to reload from the auto-save from when I entered the cave.
After popping every single chem in my inventory and pumping myself full of stand-by stimpacks I took them all one and won.
Then came the deathclaw alpha....
I had to reload 20 times before managing to take him down.
Since he could kill me with one hit I had to do it perfectly with the Ranger Takedown move.
Man after I cleared out that place I had used 80% of my aid section to stay alive.
Sure I lost a crapload of money doing it but it was fun and challenging as hell.