For quite a while now PepsiCo has been stocking coolers with summer variations of Mountain Dew, which they're really starting to do more and more each year. One of them has a history, and the other is brand-spanking new.
The first is Mountain Dew Baja Blast. This flavor has been available at the fountain of Taco Bell restaurants for over 15 years now; I remember filling my cup with the stuff as early as 1998. I'm not sure why Pepsi took over a decade to decide the sell the stuff in bottles and cans. It's possible that Taco Bell had a tight hold on the licensing of it.
After drinking the stuff for over half my life, it's still hard to pin down what exactly Baja Blast tastes like. It's turquoise/teal color is much more memorable than the flavor, despite it being outstanding(see rating below). At first taste what is perhaps most notable is that this stuff has more of a "green lollipop" lime note that just the regular Dew pan-citrus backbone. But that's not all. There are a few more subtle flavors in Baja Blast that I've spent years trying to pin down. As of now, 2015, the only ones I'm comfortable mentioning are melon, and perhaps the slightest bit of coconut. Regardless, it's grand stuff. Pick up the stuff in stores while you still can, and if you can't, find your local Taco Bell.
Mountain Dew Baja Blast:
- OutstandingOriginal Mountain Dew(for comparison):
- Great 
Mountain Dew Sangrita Blast has also been available on tap in Taco Bells for at least a year now, and it too has been issued in plastic and aluminum alongside Baja Blast for this summer, presumably. Sangrita is traditionally a fruit juice accompaniment to be sipped alongside tequila. It's a bit of a strange inspiration for a take on Mountain Dew, but it's creative, I must admit. (If you like reading about drinking liquor, check out my other blog.)
The first sip of Sangrita Blast will make clear that it's tart. I haven't had a Dew this tart since Pitch Black II. Oddly, there's just enough tartness in this mix to counter the sugar and make it seem "dry", like a dry red wine, perhaps. It's really pleasant. As for flavor, it's hard to discern, like many flavored Dews, but what I'm really getting is grenadine (the proper stuff, made from pomegranates). The grenadine flavor more or less trounces the citrus, but not in a bad way. This is one of the more classy Dews you'll find.
Mountain Dew Sangrita Blast:
- Great