If I'm on my own to choose a whole watermelon, I look for one with a shrunken and discolored stem. Like other melons, honeydews build up all their natural sugars while on the vine. They become softer and juicier after harvest, but they will never be sweeter than on the day they are picked. When ripe, the rind will be golden and feel somewhat velvety. The other ripeness clue is a sweet, heady aroma.
Casabas are large, globe-shaped melons that are slightly pointed at the blossom end.
They have a rough, furrowed, mostly yellow rind, and very little aroma. The flesh is creamy white, sweet and juicy. Crenshaw melons have a large, round base and pointed stem end. The rind is smooth and a goldish-green color. The salmon-colored flesh is juicy with a slightly spicy taste.