Is Metal Detecting allowed in Hawaii State Parks: YES, on sand beaches only.
You can find the link to the rules HERE:
Metal Detecting Devices are allowed on sand beaches only.
FMDAC Disclaimer: FMDAC assumes no responsibility for any person who knowingly or accidentally violates any state park regulation. Although FMDAC will try to keep this information current we cannot anticipate how each regulation will be interpreted by a specific park department, park employee or other government employee. It is the sole responsibility of each individual to know and obey the regulations of the park or area they are visiting and or metal detecting.