3D tracking of marine megafauna to advance movement ecology.
Modern animal tracking devices reliably record movement in horizontal and vertical dimensions, positioning movement ecology to transition towards true three-dimensional (3D) analyses. True 3D tracking, in which horizontal and vertical positions are paired through time, is particularly valuable for marine megafauna, which traverse coastal, pelagic, and aerial environments, making them ideal for illustrating how 3D data can advance movement ecology. By synthesising early approaches to 3D tracking in these taxa, we show that these studies provide ecological perspectives unobtainable from two-dimensional data, identify key barriers limiting wider adoption, and highlight emerging solutions. Broader adoption of true 3D tracking is critical for addressing remaining knowledge gaps in marine megafauna ecology and for improving conservation frameworks to protect the 3D environments these species occupy.