This source contains 100 hand-picked photo-quadrats images from Rapid Ecological Assessment (REA) surveys in Guam and the CNMI. It is assembled for Benthic Image Analysis (BIA) calibration purposes to assess inter-observer variability and bias, and improve consistency among analysts. There are 10 sets of images—including a Master “answer key”—and each analyst needs to complete this exercise prior to beginning the 2022 Mariana NCRMP BIA production series.