Soaking is very controversial but it is a very critical part of your animal's well being. This can prevent pyramiding, dehydration and illness that come as a result of dehydration.
What is Soaking?
Soaking is just letting a tortoise sit in a warm water bath. This allows them to drink freely, absorb water via the thin skin around cloaca and neck, remoisten their skin, cool off, clean up, and even relieve scratchy areas of their skin. Some tortoises will soak in their water dish, sometimes for hours at a time. Other tortoises are never seen to voluntarily soak (or even drink) and may need to be placed in a container to soak.
Babies should be soaked daily, especially if they do not soak themselves. Older than 1 year, they have already established a routine, so soaking 2-3x per week is enough.
Soaking should be about 80-85 degrees F (no more than 90 degrees F) for about 20-30 minutes of duration. Change the water if the animal relieves himself in it. I keep my soaking bowl in the enclosure, near the lamps so the water does not get cold. Make sure that the container has high walls to prevent escape and that it is not clear, to prevent them from looking out.