The travertines are a fragile natural wonder; a few simple rules protect both you and these white terraces.
The shoe rule
You walk the terraces barefoot — this isn't a tradition but a rule of protection. A small cloth bag to carry your shoes makes life much easier. The ground is hard and rough in places, slippery in others; take your time.
Water and sun
There's almost no shade on the terraces. In summer, a hat, sunscreen and water aren't a luxury but a necessity. Early morning or late afternoon hours are both cooler and safer.
Slippery ground
The stretches where the water flows can be slippery. For families with children, walking hand in hand — and pausing to find your balance before taking a photo — is enough. On my tours I know the safest and most beautiful crossings in advance.