Second Phase (Combat Diving)
Second Phase is the seven-week diving block of BUD/S, where selected candidates train on open-circuit and closed-circuit diving gear. The instruction for the programme lists physical training, distance running, swimming and the obstacle course alongside the diving itself.
What the Phase Trains
Second Phase trains candidates in open-circuit and closed-circuit diving, and MILPERSMAN 1306-1016 (10 December 2024) lists the rest of the course content with it: physical training, distance running, aquatics or swimming, and the obstacle course. It is the point in the pipeline where the water stops being an assessment and becomes a workplace. The phase exists to turn a candidate who can pass a 500-yard swim into one who can work on gear underwater as part of a crew.
Why Attrition Falls Here
The phase takes about 5% of a class, against 66% in First Phase. That is what the instruction's own wording shows: First Phase selects and prepares, while Second and Third Phase train candidates who have already been selected. Nothing about that makes the diving phase easy. It makes it instruction rather than assessment, and instruction rewards candidates who show up able to learn on a full day of physical training.
What It Asks of Your Preparation
The NSW PT Guide's weekly schedule (Table 5, page 9) puts three swims in every week, a continuous high-intensity swim on Tuesday, a long slow distance swim on Thursday and intervals on Saturday, on the days between its three runs, and its progression takes the long swim from 1,000 yards in week 1 to 3,500 yards in week 26 (Table 4, page 8). A candidate builds the aerobic base for long water work with long slow distance swims, sharpens efficiency with the combat sidestroke, and keeps running fitness for the beach and boat work that never stops. None of that needs a dive tower.
Comfort in the water is built, not granted. Long easy swims and steady breath work in a plain lap pool are the cheapest way to buy it before Coronado.
Related Terms
First Phase is the seven-week opening block of BUD/S, the phase that selects and prepares candidates physically and psychologically for the rest of the pipeline. It holds Hell Week, and it is where most of a BUD/S class is lost.
Third Phase is the final seven-week block of BUD/S, and it is the land warfare phase. MILPERSMAN 1306-1016 lists what candidates train in there: hydrographic reconnaissance, combat swimmer or diver work, land navigation, demolition, and weapons skills.
The combat sidestroke (CSS) is a hybrid swimming technique developed for military applications that combines elements of sidestroke, freestyle, and breaststroke. It is the preferred stroke for the PST 500-yard swim and the primary swimming technique used throughout BUD/S training and NSW operations.
The Long Slow Distance swim is the Thursday cardio session in the 26-week NSW preparation program. It is a continuous swim at a low to moderate intensity, and its distance grows by 100 yards every week, from 1,000 yards in week 1 to 3,500 yards in week 26.
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