Abundance data (individuals.100 m-3) of planktonic cnidarians collected during the Camadas Finas III oceanographic cruise along the North Brazilian continental shelf between the Amazon and Oyapok river mouths and equatorial Atlantic oceanic waters between 8°N, 51°W and 3.5°S, 37°W. Data was obtained during the oceanographic cruise Camadas Finas III, aboard the research vessel NHo. Cruzeiro do Sul - H38 (DHN/Brazilian Navy), performed in 9-31 October 2012. Planktonic cnidarians were sorted from zooplankton samples collected at at 44 stations in oblique hauls, using Bongo nets with 120 and 300 µm mesh and 0.3 and 0.6 m mouth diameter, respectively. The water column was sampled from near the bottom to the surface over the continental shelf and from 200 m to the surface in the offshore. The net was towed at approximately 2 knots, at various times of day and night.