The need for marine spatial planning and concerns about the environmental impacts of anthropogenic activities (including climate change, pollution and offshore industries) has led to a growing requirement for large-scale habitat characterisation to inform management, through mapping or environmental assessments. The drop camera system described here is robust, wide-field, and horizontal-facing, in either the stereo or mono-video variations. It is specifically designed for rapidly collecting benthic habitat composition and has been demonstrated to improve habitat quantification across a range of depths from 2 - 220 m. The system is ideal for collecting spatially balanced point samples over large areas, which can be logistically restrictive for other survey platforms, either due to their long deployment times (e.g. stereo-BRUVs), limit on number of ascents (e.g. scuba) or need to be tethered or supported along transects with a finite time underwater (e.g. ROV, AUV), which typically lead to nested or spatially constrained sampling (Monk et al., 2018; Shortis et al., 2008). The optional use of stereo-cameras enables the usable area of the image and range of observation to be quantified and included as an offset in analysis (e.g. when turbidity varies among sites, Broad et al., 2023). Photogrammetry of stereo images also enables the measurement of additional metrics such as algal canopy height or the dimension of benthic biota (Langlois et al., 2021; Vergés et al., 2016). These data are highly amenable for medium to large-scale habitat mapping of marine parks (Leleu et al., 2012), detection of recovery in benthic biota after trawling (Langlois et al., 2021), and environmental impact assessments of emerging industries such as offshore renewables (LaFrance et al., 2014).
