(a) Neither the owner of a cave nor his authorized agents acting within the scope of their authority are liable for injuries sustained by any person using such features for recreational or scientific purpose if the prior consent of the owner has been obtained and if no charge has been made for the use of such features.
(b) An owner of a commercial cave is not liable for an injury sustained by a spectator who has paid to view the cave, unless such injury is sustained as a result of such owner's negligence in connection with the providing and maintaining of trails, stairs, electrical wires or other modifications, and such negligence is the proximate cause of the injury.