Marine biological data from the 2004 voyage of the R/V Tangaroa (TAN0402) to the Ross Sea, Antarctica. The main objective of the New Zealand Ministry of Fisheries (now Ministry for Primary Industries) project (BioRoss) was to carry out a quantitative survey of the biodiversity of selected marine communities in the Ross Sea region, including the Balleny Islands. The survey programme was divided into two separate objectives. 1. Ross Sea component (14 days): This comprised 5 across-shelf (generally aligned SW-NE) transects from 50m bottom depth to the shelf edge (∼750m). Each transect was to be multibeamed (in an offshore direction) to establish bathymetry (& backscatter), and to be sampled along the return path within three depth strata (750-500, 500-250, 250-50m) by grab/camera, epibenthic sled/camera, and trawl. 2. Balleny Islands component (3 days): This comprised sampling seamounts associated with the Balleny Islands. Three features were targeted – the slopes of the islands of Young/Borradaile/Buckle (effectively a single seamount), Sturge Island and Balleny Seamount . On each seamount a minimum of 4 random (by depth and direction) stations were to be sampled using the three methods (grab/camera, epibenthic sled/camera, trawl).