Good Samaritan Laws protect LAYMEN, not professionals. I don't know what you do, but this is something that all professionals should keep in mind.
Actually good samaritan laws protect professionals and only sometimes laymen depending on the jurisdiction. However, they certainly don't apply in the case of a off-work dive professional being a good samaritan by escorting new divers around the park. Where they would apply in this sort of situation is if there were a accident and an off-work (professional) doctor or nurse were nearby and rendered immediate assistance.
California Health & Safety Code section 1799.102 states:
"(a) No person who in good faith, and not for
compensation, renders emergency medical or nonmedical care at the
scene of an emergency shall be liable for any civil damages resulting
from any act or omission. The scene of an emergency shall not
include emergency departments and other places where medical care is
usually offered. This subdivision applies only to the medical, law
enforcement, and emergency personnel specified in this chapter."
Laymen are also protected to the extent they don't commit gross negligence or worse:
"(b) (1) It is the intent of the Legislature to encourage other
individuals to volunteer, without compensation, to assist others in
need during an emergency, while ensuring that those volunteers who
provide care or assistance act responsibly.
(2) Except for those persons specified in subdivision (a), no
person who in good faith, and not for compensation, renders emergency
medical or nonmedical care or assistance at the scene of an
emergency shall be liable for civil damages resulting from any act or
omission other than an act or omission constituting gross negligence
or willful or wanton misconduct. The scene of an emergency shall not
include emergency departments and other places where medical care is
usually offered. This subdivision shall not be construed to alter
existing protections from liability for licensed medical or other
personnel specified in subdivision (a) or any other law."