Figure 2. (A) Dive angle, (B) vertical transit rate, (C) swim speed, (D) surge acceleration and (E) foot-stroke frequency, in relation to current dive depth (>5 m), for the descent and the ascent phases and for different maximum dive depth categories.

Each value was calculated as the mean of individual means. Because stroking activity is so intense during the first 1–2 s of the descent phase (strong and frequent feet kicks), it was not possible to detect the strokes occurring during this period. Consequently, the first current dive depth category (10 m) ranges from 10–15 m, the second (20 m) from 15–25 m, and so on. A maximum dive depth class stood out (120–130 m); for this class, parameters derive from two dives carried out by the same individual.