Is Metal Detecting allowed: YES with permit.
Below is an excerpt from the State Park regulations found HERE.
7:2-2.16 Metal detectors
A person shall not use metal detectors or similar devices without a permit issued by Superintendent or designee. The permit may limit the location, hours, and days of use. A permit will not be issued for use in areas of significant historical or other value, or where such use would be incompatible with protection of the resource and/or interfere with public use of the facility.
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.