Sitting in a lotus position in the center of his usual training area, Desmond was in some kind of meditative state, the mana in the water around him agglomerating into small, airborne clumps that solidified over time in a single body of water.
In an undulating and changing way, Desmond captured his will in the water trying to represent the image on which he was concentrating, according to Sasha's advice, Desmond was trying to represent something significant for him that in his mind is related to concepts attributable to the Water.
It wasn't really a surprise that the image in Desmond's mind was a woman and it was even less of a surprise that the woman in question was Claire. Following the image in Desmond's mind, the water began to mold under the constant pressure of his will gradually taking on a human form, but as soon as Desmond tried to imprint Claire's finer details the water figure collapsed due to Desmond's lack of control.