Cancer, Scorpio, Pisces. The signs that absorb, retain and eventually dissolve.
Water signs sit at 90°, 210° and 330°. Cancer opens at the June solstice, Scorpio sits in the middle of autumn, Pisces dissolves the year at its end.
Water is the element that contains the year's high point and its final degree — Cancer at the Sun's greatest northern declination, and Pisces at 29°59', immediately adjacent to 0° Aries where the circle restarts.
Each water sign is square or opposite a sign of every other element except its own, which is the structural basis for the traditional pairing of water with earth (sextile, 60°) and its traditional friction with fire and air.