What would happen if we dug to the mantle?

Excuse me, but I was wondering, what would actually transpire if we were to embark on a journey towards the mantle of the Earth? It's a fascinating concept, digging deep into the core of our planet, but I'm at a loss as to what the consequences might be. Would the heat be unbearable? Would we encounter unusual geological formations? Or is there something else entirely that we haven't even considered? Your insights would be greatly appreciated.