At present there is a wide catalogue of watermelon varieties, that are classified according to different agronomic characteristics, such as the colour of the rind, the size of the fruit, shape, taste, etc. There are also seedless varieties of watermelon.

Colour of the skin: it ranges from pale green to dark green. It may be uniform all over the fruit or mottled.
Size of the fruit: it varies, from 2 to 15 kg.
Shape of the fruit: spherical, oblong or elongate.
Taste of the flesh: it is more or less sweet.
Thickness of the rind: between 0.5 and 3mm.
Quantity and size of the pips: at present there are seedless varieties of watermelon.
Earliness.

Taking these characteristics into account, some of the varieties cultivated in Spain are the following:

Varieties of rounded fruit and early cycle: "Sugar Baby", "Catalana Precoz" and "Perla Negra’, all of dark green rind; "Yellow Doll", of pale green rind with streaks, and yellow pulp, and "Rubin", of pale green rind.

Varieties of average-late cycle and rounded fruit: "Pileña’, "Sayonara’ and "Dulce de América’, both with dark green rind, and "Imperial", with dark green or clear-green streaked rind.

Varieties of elongate fruit and early cycle: "Klondike rayada’, with a rind of green colour, mottled in dark green, and "Prince Charles", with a greyish green rind.

Varieties of lengthy fruit and average-late cycle: "Fairfax" and "Congo’, of pale green rind, with darker green streaks; "Blacklee’, of dark green rind; "Charleston Gray", of pale green rind, and "Sweet Meat II WR", greyish rind with dark green streaks.

Apart from these varieties, there are seedless watermelons, like "Reina de Corazones", bearing rounded fruits of pale green colour; ‘Sin", rounded fruits of a dark green colour, "Rey de Corazones" and " Fummy".