It sounds great and as long as you are not claustrophobic...could be really relaxing.
Hopefully your sister can give you more details so you can decide if it's something you want to try!
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT