Specific activities of natural ( 40 K, 226 Ra, and 232 Th) and anthropogenic ( 137 Cs) radionuclides in 230 surface soil and beach sand samples collected from the densely populated areas of industrial activities in Rayong Province, Thailand, were analyzed. Experimental results were obtained using a high-purity germanium detector and gamma spectrometric analysis system. The frequency distributions of the four radionuclides were investigated and calculated as suitable medium values of all distributions. According to asymmetrical distribution, medium values of the specific activities of all required radionuclides should be median values. Furthermore, the median values of the three natural radionuclides were also used to evaluate absorbed dose rates in the air (D), radium equivalent (Ra eq ), external hazard index (H ex ), annual effective dose rate (AED out ), and excess lifetime cancer risk (ELCR) in the studied areas. The results were compared with data obtained from the annual report of Thailand's Office of Atoms for Peace, the global radioactivity measurements, and the evaluations and recommended values proposed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). It was found that most of the results were significantly lower than the recommended values of UNSCEAR except for the median value of specific activity of 226 Ra. Moreover, the radioactive contour map for the investigated areas was constructed.