South of Hanoi, the landscape shifts into something that doesn't seem entirely real — limestone peaks rising out of rice paddies, Tam Coc’s river caves that swallow you in darkness before releasing you back into the light. The climb to Hang Múa Peak earns you a view that stretches across the entire valley, the river below threading quietly through it all. The Ninh Binh province rewards the people who slow down enough to let it.