How do you blow them up? Is there somewhere where i can craft bombs?

You need to buy the Grapeshot bomb diagram from cedic , then go to alchemy section and you can craft the bombs these can then be used to blow up the nest entrances

thanks

You must craft a bomb called Grapeshot (schematics can be bought from Cedric). Then when you approach a nekker nest you just click on the left mouse when the icon appears and Geralt will deploy a bomb to blow it up.

Actually what you need to use is mentioned in the character sheet-->attributes-->knowledge section under the nekker entry.

I was kinda wondering about those bombs myself. I was down in the tunnels as well and those things are becoming a nuisance. You can also blow up the tunnels I think.

If you cant find the nests, save and exit to the menu, seems to reset the non blown up ones.

Go to town and buy grapeshot bombs. Or craft a few yourself.

The nekker nests are spotted by the ..... dozens of nekkers charging towards you. Happy farming :)