The more than 1200 cultivars of watermelon range in weight from less than 1 kg to more than 90 kilograms (200 lb); the flesh can be red, pink, orange, yellow or white.

The 'Carolina Cross' produced the current world record for heaviest watermelon, weighing 159 kilograms (351 pounds). It has green skin, red flesh and commonly produces fruit between 29 and 68 kilograms (65 and 150 lb). It takes about 90 days from planting to harvest.

The 'Golden Midget' has a golden rind and pink flesh when ripe, and takes 70 days from planting to harvest.

The 'Orangeglo' has a very sweet orange flesh, and is a large, oblong fruit weighing 9–14 kg (20–31 lb). It has a light green rind with jagged dark green stripes. It takes about 90–100 days from planting to harvest.

We are most familiar with the vivid reddish-pink flesh dotted with black seeds, but there are also white, pink, yellow and orange-fleshed varieties, both with seeds and without. Color, size and shape have little bearing on the flavor of the flesh between differing varieties.

Seedless varieties are not truly seedless, but actually do contain tiny, white, edible immature seeds in lesser amounts than traditional watermelons.

More Info: en.wikipedia.org