A typical dive cycle of a blue whale is a series of surface dives followed by a deep dive.
The time period between the first surfacing after a deep dive and the last surfacing before the next deep dive was called a surfacing bout.
Based on this classification of dives, a number of metrics were estimated to describe the diving and surfacing characteristics of the blue whales during a follow: mean IBI, bout duration and number of surfacings in a bout.
In the event that a whale watch boat (or multiple) was present within 300 m of a surfacing whale, the research vessel would maintain a distance of 300 m from the whale and only document fluking behaviour.
No other metrics were gathered during these encounters due to the risk of missing surfacings in the presence of multiple boats.