There can be up to 6 or 8 people in the salt cave at a time.  By calling to make reservations, we strive to give people as much privacy as possible.  The only way to ensure complete privacy is to have a reservation for 6 or more people.  Ultimately, a minimum of 6 people must be paid for to guarantee the cave to yourself for a session. (Most places charge $150 to reserve a salt cave)