A visual survey method specifically designed for REEF volunteer data. During RDT surveys, divers swim freely throughout a dive site and record every observed fish species that can be positively identified. The search for fishes begins as soon as the diver enters the water. The goal is to find as many species as possible so divers are encouraged to look under ledges and up in the water column. At the conclusion of each survey, each recorded species is assigned one of four abundance categories based on about how many were seen throughout the dive (single (1); few (2-10), many (11-100), and abundant (>100)).