In the leap to plunge, the legs must be kept together, the arms close,
and the plunge made either with the feet or the head foremost. With
the feet foremost they must be kept together, and the body inclined
backwards. With the head foremost, the methods vary.
In the deep plunge, which is used where it is known that there is depth
of water, the swimmer has his arms outstretched, his knees bent, and
his body leant forwards (Plate XXVI. fig. 1,) till the head descends
nearly to the feet, when the spine and knees are extended. This plunge
may be made without the slightest noise. When the swimmer rises to the
surface, he must not open his mouth before previously repelling the
water.
In the flat plunge, which is used in shallow water, or where the depth
is unknown, and which can be made only from a small height, the swimmer
must fling himself forwards, in order to extend the line of the plunge
as much as possible under the surface of the water; and, as soon as he
touches it, he must keep his head up, his back hollow, and his hands
stretched forward, flat and inclined upward. He will thus dart forwards
a considerable way close under the surface, so that his head will reach
it before the impulse ceases to operate. (Plate XXVI. fig. 2.)