Learn the freediving fin kick: a long, straight leg stroke from the hip with long fins in horizontal and vertical positions, with milestones and safety rules.
How do you move forward in freediving with little force and little oxygen? The honest answer: with a long, loose fin kick from the hip. Scuba divers kick short and compact. In freediving you swim on one breath, so every muscle tension counts. Relaxed, straight legs save oxygen you will urgently need later.
How much does technique cost? A study of 22 freedivers in a 50-metre pool measured the energy cost of a dynamic apnea swim. With bi-fins the cost per kilo and metre was 7.4 joules, with a monofin 5.5 joules, the difference due to higher oxygen debt and more lactate [1]. For beginners this does not mean buying a monofin right away. It means: the kick makes a measurable difference. In another investigation with ten professional divers, flutter, dolphin and breaststroke kicks with gear were comparable in speed [2].
This guide explains the basic technique with long fins. It does not replace a freediving course. Important upfront: this is technique in a pool and sheltered water, not depth. Whoever learns the movement cleanly first saves strength and air later. The first pool sessions belong to the feeling of length and glide, not distance.
Put on the fins. Body stretched, head neutral in line with the spine, arms long in front of the head or at your sides. Look slightly downward. Milestone: you glide calmly without tipping.
Hold the pool edge and let your legs work only from the hip. Knees slightly bent but not "pedalling". The kick travels like a wave through the legs to the fin tip. Milestone: you kick ten times without your knees buckling.
A freediving kick is bigger and slower than a scuba flutter. Legs stay as straight as possible, feet loose. Hectic movement burns oxygen. Milestone: you manage 25 metres without your stroke rate rising.
Choose a tempo you can hold with a calm pulse. If you have to speed up mid-way, the start was too timid or the technique too restless. In the dynamic apnea study, energy cost per metre was the same at 50 and 100 metres [1]. So: even beats jerky.
Kick upright on the line in a deep pool. Body stretched, head neutral, fins beat small and stable. With the line you see how the kick carries you. Milestone: you stay upright for five metres in a row without sinking.
From horizontal to vertical and back, without pause or jerk. According to DAN, surfacing is the most critical part of a vertical freedive, and most incidents happen in the last third of the ascent [5]. Practise it with a buddy who watches you.
Act as if you were asleep. The best fin-kick posture is the one where face, neck and hands are completely relaxed. Try it in the pool on one breath and observe: the looser the upper body, the more fluid the kick. One more trick: let the fins do the work and think length instead of force. And film yourself once from the side: many only see on video that the knees bend a lot or the feet droop.
Long, calm strokes from the hip with straight legs and loose feet. It differs from the short flutter in scuba by longer strokes and relaxation.
No. Bi-fins are enough to start. A study found that the monofin costs less energy per metre in dynamic apnea, but that is a topic for advanced divers [1].
That is individual. Many notice after a few pool sessions that the kick gets calmer (rule of thumb).
In competitions, disciplines without fins had clearly more losses of consciousness than those with fins [3]. For beginners it still applies: only with supervision.
Because you swim on one breath. In the dynamic apnea study, personal best correlated better with distance per oxygen used than with pure energy cost per metre [1]. In other words: whoever spares oxygen goes farther.
Dynamic Apnea (DYN): Distance Swimming in the Pool on One Breath