Cronvangr Broodlair is a dungeon in The Elder Scrolls V: Skyrim
Connected to Cronvangr Cave
Head inside to the North. After a corner or two you will encounter a Frostbite Spider. There is another just around the next corner. Look to the South from there. You will find a web covered chest. Take a swing or two with your sword or use some fire magic to burn through it. Open the chest for some gold or other loot. Follow the corridor to the next large room.
In this room you will encounter a Giant Frostbite Spider with several regular Frostbite Spiders backing it up. Try to attack them from a distance at first to thin the numbers. After that, go for the large Boss spider.
In the Southwest corner you will find the boss chest. Open it up for some nice loot. Search around this room for any other mission objectives that you might have. You can also find a Moonstone Ore Vein in this room as well.
Take the slope up to the Northwest to quickly get back to the first area, the Cronvangr Cave.